Introduction to

Medical Terminology
A Course Companion

Peter Reuter, M.D., Ph.D.

Valerie Weiss, M.D., M.S.
 Module 1 Introduction to Medical Terminology

1.1 Module Outline

Becoming a knowledgeable healthcare provider is much easier once you understand how word parts work together to form
medical terms.
• Module Objectives
• Introduction
• Word Roots
• Prefixes
• Suffixes
• Abbreviations, Acronyms, and Symbols
• Eponyms, Antonyms, and Synonyms
• Analyzing and Building Medical Terms
• Review Your Knowledge
• Test Your Knowledge

1.2 Module Objectives

Upon completion of this module, you will be able to:
• Identify the roles of the word parts in forming medical terms.
• Demonstrate the ability to comprehend a new medical term knowing the commonly used prefixes, word roots, and
suffixes introduced in this module and the appendix of this book.
• Recognize the importance of spelling in using medical terminology.
• Define commonly used prefixes, word roots, and suffixes.
• Create medical terms related to Health Sciences by combining prefixes, word roots, and suffixes.
• Demonstrate your understanding of the content of this module by completing the Test Your Knowledge section at the
end of the module.

1.3 Introduction
The vocabulary of the Health Sciences contains words from many fields (for example, Anatomy, Physiology, Pathology,
Pharmacology, and Psychology) that have roots in a number of languages. However, the two most common languages from
which terms are traditionally derived are Latin and Greek. Latin was the predominant language for written communication for
more than a thousand years, especially during the time when the foundations of modern sciences, including medicine, were
laid. Even now, newly discovered structures or diseases are sometimes named using Latin or Greek word parts, although
clinical medicine has been shifting gradually towards using English terms over the past decades.
Memorizing every single medical term is not the best approach to becoming a competent healthcare provider. While we need
to learn and know basic prefixes and suffixes as well as the major combining forms, it is important for students to understand
the structure of medical terms.
A medical term may have three parts — a prefix, the word root, and a suffix. Knowing the meaning of each will help you to
understand a variety of terms. Prefixes are found at the beginning of the word and modify the word’s meaning. Suffixes are
found at the end of a word. They also modify the word’s meaning.
We will look at the different word parts and at how to breakdown (analyze) medical terms as well as how to create new ones.
You will be able to practice your analytical and creative skills in the Review Your Knowledge section below.

1.4 Word Roots

The word root of a medical term is the foundation of a word that gives it meaning. Word roots typically describe the
part of the body or organ involved.

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Module 1 introduction to Medical Terminology

• For example: cardi means heart, gastr means stomach, and neur means nerve.

Word roots are usually combined with a vowel at the end (often an “o”) so that a suffix beginning with a consonant can be
added. When word roots are written in this way, they are called combining forms. Thus, the whole term when put together
as one word can be easily pronounced.

• For example: cardi(o) means heart, gastr(o) means stomach, and neur(o) means nerve.

What are the rules for using combining form vowels?

1. A combining vowel is used when the suffix begins with a consonant.

• For example, when the word root hem(o), meaning blood, is combined with the suffix –lysis, meaning destruction,
the combining vowel “o” is used because -lysis begins with a consonant. Hemolysis is a medical term that
describes the destruction of red blood cells.
2. A combining vowel is not used when the suffix already begins with a vowel.
• For example, when neur(o), meaning nerve, is combined with the suffix –itis, meaning inflammation, no combining
vowel is used because -itis already begins with a vowel. Neuritis is a medical term that means an inflammation of a
nerve or nerves.
3. A combining vowel is used when two or more word roots are joined.
• For example, we understand gastroenteritis to mean an inflammation of the stomach and the small intestine. We
combine the word roots gastr(o), meaning stomach, and enter(o) meaning small intestine. A combining vowel is
not used after enter(o) because it is joined with the suffix –itis, meaning inflammation, which already begins with a
vowel.
Each module of this Course Companion will introduce the word roots as they relate to the various body organs and systems.

Table 1.1 Word Roots/Combining Forms

Combining Form(s) Meaning Example(s)
alg(o)-, alge-, algesi(o)- Pain Myalgia = pain in a muscle
arthr(o)- Joint Arthritis = inflammation of a joint
bacteri(o)- Bacteria Bacteriuria = bacteria in the urine
blephar(o)- Eyelid Blepharoptosis = drooping of the eyelid
cerebr(o)- Cerebrum Cerebrovascular = relating to the blood vessels of the brain
cyan(o)- Blue Cyanosis = blue discoloration of the skin from a lack of
oxygen
dermat(o)-, derm(o)- Skin Dermatologist = physician who specializes in diagnosing and
treating disorders of the skin
erythr(o)- Red Erythrocyte = red blood cell
gluc(o)- Sugar, glucose Glucosuria = sugar in the urine
leuk(o)- White Leukemia = a white blood cell cancer
melan(o)- Black Melanocyte = a cell responsible for producing skin pigment
myel(o)- Spinal cord Myelopathy = disease affecting the spinal cord
ophthalm(o)- Eye Ophthalmologist = specialist for the study and treatment of
disorders of the eye
pancreat(o)- Pancreas Pancreatitis = inflammation of the pancreas
phon(o)- Voice Dysphonia = any voice impairment
poli(o)- Gray Poliomyelitis = inflammation of the gray matter of the spinal
cord

1.5 Prefixes
A prefix is added to the beginning of the word to influence the meaning of the word root. Prefixes usually indicate the
location, time, number, or status.
Some examples of prefixes are:

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 • Peri- (meaning around) as in pericardium; the word pericardium refers to the membranous sac around the heart.
• Epi- (meaning above) as in epigastric; the term epigastric describes the area above the stomach.
• Poly- (meaning many) as in polyneuritis; polyneuritis describes an inflammation of many nerves.
• Hemi- (meaning half) as in hemiplegia; hemiplegia describes a paralysis affecting one side of the body only.
• Endo- (meaning inside) as in endocrine; the word endocrine means secreting into the inside of the body.
• Exo- (meaning outside) as in exocrine; the word exocrine means secreting onto the outside of the body.
• Intra- (meaning inside) as in intracellular; the word intracellular means inside a cell.
• Extra- (meaning outside) as in extracellular; the word extracellular means outside of a cell.
Some prefixes can have opposing or contrasting meanings; it is important to be aware of that. For example, the prefix intra-
means inside, the prefix extra-, outside. It makes all the difference in the world, whether a substance is found inside or
outside a cell. Endo- and exo- are another pair of contrasting prefixes. Endocrine glands secrete their products into the
blood, exocrine glands, onto inner and outer body surfaces. Table 1.2 lists other opposing or contrasting prefixes common in
medical terminology.

Table 1.2 Contrasting Prefixes

Prefix Contrasting Prefix
ab- to move away (from) ad- to move toward
abduct = to move away from the midline of the body adduct = to move toward the midline of the body
dys- abnormal, difficult eu- normal, good
dyspnea = difficult or labored breathing euphoria = a state of well being
hyper- excessive, above normal hypo- below normal
hypertension = high blood pressure hypotension = low blood pressure
pre- before post- after
prenatal = before birth postmortem = after death
tachy- fast brady- slow
tachycardia = fast heartbeat bradycardia = slow heartbeat

1.6 Suffixes
A suffix is added to the end of the word root and usually indicates a procedure, condition, disorder, or disease. A
suffix can totally change the meaning of a word root.
• For example:
• -megaly (meaning enlargement) as in cardiomegaly; the term cardiomegaly means an enlargement of the heart.
• -algia (meaning pain and suffering) as in gastralgia; the term gastralgia means pain in the stomach.
• -itis (meaning inflammation) as in tonsillitis; the term tonsillitis means an inflammation of the tonsils.
• -ectomy (meaning surgical removal of) as in tonsillectomy; the term tonsillectomy means surgical removal of the
tonsils.
A suffix can make the word root a noun or an adjective.
• For example:
• -um acts as a noun ending as in cranium; the term cranium names the part of the skull that encloses the brain.
• -ac and –al act as an adjective ending as in cardiac and renal; the term cardiac means relating to the heart, the
term renal relating to the kidney.

Many suffixes are related to specific disease conditions or pathology (see Table 1.3). Path(o) is the word root for disease and
–ology is the suffix that means the study of. Therefore, pathology is the study of diseases.

Likewise, a similar suffix is –ologist that refers to a medical specialist. For example, a cardiologist specializes in diagnosing
and treating conditions of the heart.

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Module 1 introduction to Medical Terminology

Table 1.3 Common Suffixes related to Disease Conditions

Suffix Meaning Example(s)
-algia Pain Neuralgia = pain in the nerves
-cele Abnormal protrusion Myocele = abnormal protrusion of muscle; hernia
-emesis Vomiting Hyperemesis = excessive vomiting
-itis Inflammation Laryngitis = inflammation of the larynx (voice box)
-lysis Destruction Hemolysis = destruction of red blood cells
-malacia Softening Osteomalacia = softening of the bone
-megaly Enlargement Cardiomegaly = enlargement of the heart
-necrosis Tissue death Arterionecrosis = tissue death of an artery or arteries
-osis Abnormal condition Gastrosis = any abnormal condition of the stomach
-oma Tumor Carcinoma = a malignant tumor
-pathy Disease, suffering Myopathy = disease of the muscle
-ptosis Sagging or drooping Blepharoptosis = drooping of the upper eyelid
-sclerosis Abnormal hardening Arteriosclerosis = hardening of an artery or arteries
-stenosis Abnormal narrowing Arteriostenosis = narrowing of an artery or arteries

Some suffixes help identify a particular procedure that is performed on the body part relating to the organ system’s word root.
Table 1.4 lists commonly used suffixes related to surgical and nonsurgical procedures.

Table 1.4 Common Suffixes related to Procedures

Suffix Meaning Example(s)
-centesis Surgical puncture Abdominocentesis = surgical puncture of the
abdominal cavity to remove fluid
-ectomy Surgical removal Tonsillectomy = surgical removal of the tonsils
-gram A record Electrocardiogram = a recording of the
heartbeat
-graphy The process of recording Coronary angiography = the process of making
a radiographic study of the coronary arteries
after inserting a contrast dye
-ostomy Surgical creation of an artificial opening to the Colostomy = surgical creation of an artificial
body surface excretory opening between the colon and body
surface
-otomy Cutting or surgical incision Phlebotomy = the puncture of a vein for the
purpose of drawing blood
-plasty Surgical repair Valvuloplasty = surgical repair or replacement
of a faulty heart valve
-scopy Visual examination Laparoscopy = visual examination of the
interior of the abdomen with a laparoscope

Some suffixes begin with two letter “Rs.” These suffixes are sometimes referred to the “double RRs.” It is important for you
to understand the differences among these suffixes.

Table 1.5 “Double R” suffixes

Suffix Meaning Example(s)
-rrhage, -rrhagia Bleeding (sudden, severe flow) Hemorrhage = sudden, severe loss of blood
-rrhaphy Surgical suturing Myorrphaphy = surgical suturing of muscle
-rrhea Flow (of body fluids) Amenorrhea = absence of menstrual flow
-rrhexis Rupture Myorrhexis = rupture of muscle

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1.7 Abbreviations, Acronyms, and Symbols
There may not be another field that uses more abbreviations and acronyms than healthcare, and it is of paramount
importance for you to know as many as possible and to use them correctly. This module introduces a limited number of
abbreviations, acronyms, and symbols only. Each module has its own, special list and there is a list of Acronyms,
Abbreviations, and Symbols in the Appendix.
• An abbreviation is a shortened form of a word or phrase. For example, Dr. stands for Doctor and epi for
epinephrine. An abbreviation is also called a contraction or short form.
• An acronym is a word formed from the initial letters of other words; it is pronounced as a word. For example.
AIDS stands for Acquired Immune Deficiency Syndrome. Acronyms are sometimes incorrectly called abbreviations.
• Symbols usually consist of one or more letters and/or numbers that represent an object, function, or process.
For example, in chemistry the letter combination “Na” is the symbol for the element “sodium” (from Latin natrium).
Students may not be already familiar with the meaning of each term in Table 1.6, but they are commonly used in the health
professions and will be defined in future modules.

Table 1.6 Commonly Used Abbreviations, Acronyms, and Symbols

Acronym/abbreviation/symbol Meaning
a.c. before meals
ad lib as desired, as needed
bid, b.i.d. twice a day
BP blood pressure
bpm beats per minute
CA, ca cancer
CBC complete blood count
CNS central nervous system
C/O complains of
COPD chronic obstructive pulmonary disease
CVA cerebrovascular accident (stroke)
D&C dilation and curettage
DX diagnosis
ECG, EKG electrocardiogram
EEG electroencephalogram
Fe iron
FH family history
g gram
GERD gastroesophageal reflux disease
GI gastrointestinal
GU genitourinary
GYN gynecology
H&P history and physical
h.s. at bedtime (hour of sleep)
Hx history
I&D incision and drainage
ICU intensive care unit
IM intramuscular
IV intravenous

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Module 1 introduction to Medical Terminology

KCl potassium chloride

kg kilogram
L liter
mg milligram
MI myocardial infarction
mL, ml milliliter
NaCl sodium chloride
NPO, npo nothing by mouth
oint ointment
OR operating room
OTC over the counter
p.c. after meals
PE physical exam
PMH past medical history
p.o., PO by mouth, orally
POSTOP; postop postoperative
PREOP; preop preoperative
PRN, prn whenever necessary
qd, q.d. every day
qid. q.i.d. four times a day
Rx prescription
SOB shortness of breath
subq, SubQ, subcu subcutaneous
susp suspension
tab tablet
Tid, t.i.d. three times a day
TX treatment
U/A urinalysis
URI upper respiratory infection
US ultrasound
UTI urinary tract infection

1.8 Eponyms, Antonyms, and Synonyms

An eponym is a term or word based on or derived from a person's name. For example, Lou Gehrig’s disease (or
amyotrophic lateral sclerosis) was named after an American baseball player who battled the disorder. The Eustachian tube
connects the nose and the middle ear; it was named after the Italian anatomist Bartolomeo Eustachi.
Antonyms are words opposite in meaning to another. For example, good and bad are antonyms, as are long and short or
wide and narrow.
Synonyms are words or phrases that have exactly or nearly the same meaning as another word or phrase. For example,
shinbone and tibia are synonyms, as are thigh bone and femur.
A thesaurus is collection of words, terms or phrases that have the same (synonyms) or opposite meaning (antonyms).

1.9 Plural Forms

The plural form of most nouns is created simply by adding the letter ‘s’. However, there are a number of
exceptions of this rule. Table 1.7 lists irregular plural forms commonly found in medical terminology.

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 Table 1.7 Irregular Plural Forms
Singular Example Plural Example
-a vertebra -ae vertebrae
-is diagnosis -es diagnoses
-en lumen -ina lumina
-ma stigma -mata stigmata
-on phenomenon -a phenomena
-um serum -a sera
-ex, -ix, -yx index -ices indices
-nx phalanx -nges Phalanges
-us* thrombus -i thrombi
* exceptions virus (viruses) and sinus (sinuses)

1.10 Analyzing and Building Medical Terms

As already mentioned above, a medical term may have three parts − a prefix, the word root, and a suffix. When analyzing an
unfamiliar medical term, try to identify at least one component you may know. For example, if you are trying to work out the
meaning of the word “osteonecrosis,” you may already know “osteo” as a combining form with the meaning of “bone.”
“Necrosis” could be a suffix or it could consist of the combining form “necr(o)” and the suffix “-osis.” Look up “necrosis” in the
list of Commonly Used Adjectives, Prefixes, and Suffixes in the Appendix. It is defined as “tissue death.” Now you can put it
all together: osteo (bone) + necrosis (tissue death) = bone tissue death, which is correct.
Sometimes it may be more difficult to separate a term into its parts. For example, “epididymitis” could be separated into
“epi-didym-itis” or “epidydim-itis.” In such a case, use either the list in the appendix of this book or a dictionary to look up
“epi” and “epididym” to find the most likely meaning. You come to: “epididym(o)-“ (epididymis) + “-itis" (inflammation) =
inflammation of the epididymis (we will learn in Module 16 what this actually is).
Words with a very short or unusual prefix, for example “apnea” (a- no, -pnea breathing) can make it difficult to identify the
word parts. This can also be a problem with rather long terms that are made of multiple combining forms and a suffix, such
as “otorhinolaryngologist”: oto (ear) + rhin(o) (nose) + laryng(o) (throat) + -ologist (specialist) = Ear, Nose and Throat
(ENT) specialist).
Creating new terms is fairly easy as long as we remember that medical vocabulary has a different structure than English
vocabulary. For example, in English we use “inflammation of” and “removal of,” whereas in medical terminology “of” is
discarded and “inflammation” and “removal” are moved to the end of the word. Thus, the terms for inflammation (“-itis") and
removal (“-ectomy”) of the stomach (“gastr(o)”) are “gastritis” and “gastrectomy,” respectively.
You should be very careful about word elements that have a similar spelling, yet totally different meanings. For example,
“ped(o)” relates to the foot, but “pedi(a)-“ to children or childhood.
Let’s now create a term for the cells that create a dark (black) pigment. The prefix with the meaning “black” is “melan(o)-“
and the suffix for “cell” is “-cyte.” Together, they form the term “melanocyte.” To indicate the plural form, add an “s” at the
end. As you will see in Module 5, melanocytes produce the pigment melanin that plays an important part in our skin and hair
color.
What could the medical term be for feeling good? For example, after watching your favorite team win the Super Bowl? The
combining form for “feeling or mental state” is “-phoria,” and the prefix for “good, well or easy” is “eu-.” If we combine them,
we get the word “euphoria,” which describes a feeling or state of intense excitement and happiness. If our team lost,
however, we replace “eu-“ with “dys-“ and come to “dysphoria,” a profound feeling or state of dissatisfaction.
Most of the time you will be tempted to go ahead and just look up the meaning of a word online or in a book/dictionary as this
is faster and easier than trying to work out the meaning yourself. However, this is an approach you should only choose once
you have completed this course. Knowing as many word roots, prefixes, and suffixes as possible will help you understand
not just the material covered in this course, but also of all related courses and literature you will read now and in the future.
You will, for example, be more likely to master Coding and Billing and less likely to make coding mistakes when you know
the meaning of disorders. Therefore, we encourage you to take the time to complete the Review Your Knowledge section
below. It will also help you perform well on the Test Your Knowledge section and the online quiz as well as the final exam
and certification exams.