/ Dictionary / Index C cotyledon: Meaning and Definition of Find definitions for: cot•y•le•don Pronunciation: (kot"l-ēd'n), [key] — n. Bot. the primary or rudimentary leaf of the embryo of seed plants. any of several lobules of the placenta. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: cotyledon (Thesaurus) Coty cotyloid Related Content Daily Word Quiz: abstain Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language