have to

• hafta (colloquial)

Dates back at least to the Old English habban + tō construction, with the same meaning as sense 1 below.

• (UK) IPA^(key): /ˈhæv.tuː/ (careful)
• (General American) IPA^(key): /ˈhæf.tu/ (careful)

• Audio (US):

  (file)

• (UK, General American) IPA^(key): /ˈhæf.tə/ (relaxed pronunciation)

have to (third-person singular simple present has to, present participle having to, simple past and past participle had to)

1. Must; need to; to be urged to; to be required to; indicates obligation.

   Synonyms: need to, have got to, got to, gotta

   You have to wear a seat belt.

   I have to go to the bathroom.

   I just have to have that shirt.

   • 1897 December (indicated as 1898), Winston Churchill, chapter I, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd., →OCLC:

     I was about to say that I had known the Celebrity from the time he wore kilts. But I see I will have to amend that, because he was not a celebrity then, nor, indeed, did he achieve fame until some time after I left New York for the West.

   • 1951 September, “Notes and News: New Station for Glasgow Zoo”, in Railway Magazine, page 639:

     Before the new station could be built, a private overbridge had to be raised, and the railway regraded.

   • 2013 July-August, Henry Petroski, “Geothermal Energy”, in American Scientist, volume 101, number 4:

     Energy has seldom been found where we need it when we want it. Ancient nomads, wishing to ward off the evening chill and enjoy a meal around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between sticks to kindle a flame.

   • 2023 December 27, Stephen Roberts, “Bradshaw's Britain: the way to Weymouth”, in RAIL, number 999, page 55:

     The railway ran through the resort's narrow streets up to Weymouth Quay station, with thoughtlessly parked vehicles sometimes having to be bumped out of the way.

2. (with be) Must; expresses a logical conclusion.

   Synonyms: be bound to, have got to, got to, gotta, must

   that has to be the postman;  it has to be an electrical fault

• have is always followed by an infinitive verb, unless the verb is assumed:

I don't want to go to school, but I have to.

• Appendix:English modal verbs
• Appendix:English tag questions

• Collins English Dictionary
• “have to”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.
• “have to”, in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present.