/ Dictionary / Index D decadal: Meaning and Definition of Find definitions for: dec•a•dal Pronunciation: (dek'u-dl), [key] — adj. of or pertaining to a decade. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. deca- decade Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language