/ Dictionary / Index D deca-: Meaning and Definition of Find definitions for: deca- Pronunciation: [key] a combining form meaning “ten,” used in the formation of compound words: decapod. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. dec- decadal 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