/ Dictionary / Index P precipitin: Meaning and Definition of Find definitions for: pre•cip•i•tin Pronunciation: (pri-sip'i-tin), [key] — n. Immunol. an antibody that reacts with its specific antigen to form an insoluble precipitate. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: precipitin (Thesaurus) precipitation precipitinogen Related Content Daily Word Quiz: opulent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language