/ Dictionary / Index C cycloaddition: Meaning and Definition of Find definitions for: cy•clo•ad•di•tion Pronunciation: (sī"klō-u-dish'un, sik"lō-), [key] — n. Chem. the formation of a cyclic compound by the addition reaction of unsaturated molecules. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. cyclo cycloaliphatic Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language