h/o

h/o

1. (Internet slang, text messaging) Abbreviation of hold on.

h/o

1. (medicine) Abbreviation of history of.
   • 2009, Sarah T. Melton, Cynthia K. Kirkwood, “Obsessive-Compulsive Disorder”, in Terry L. Schinghammer, Julia M. Koehler, editors, Pharmacotherapy Casebook: A Patient-Focused Approach‎^[1], 7th edition, McGraw Hill, →DOI, →ISBN, page 194:

     H/O complex partial seizures in childhood and teen years (off medication and seizure-free for 7 years)

• OH, oh, Oh, -oh, Oh.