/ Dictionary / Index C ctn: Meaning and Definition of Find definitions for: ctn Pronunciation: [key] — Trig. Trig. cotangent. ctn. Pronunciation: [key] — pl. ctns. carton. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ctg. ctr. Related Content Daily Word Quiz: fresco Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language