/ Dictionary / Index C cosec: Meaning and Definition of Find definitions for: co•sec Pronunciation: (kō'sēk"), [key] — n. cosecant. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: cosec (Thesaurus) cose cosecant Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language