cotyledon

UK: /ˌkɒtɪˈliːd^ən/ US: /ˌkɑtəˈlidən/ ,(kot′l ēd′n)

WordReference Random House Learner's Dictionary of American English © 2026

cot•y•le•don /ˌkɑtəˈlidən/   n. [countable]

1. Botany the primary leaf of the embryo of seed plants.

WordReference Random House Unabridged Dictionary of American English © 2026

cot•y•le•don  (kot′l ēd′n), n. [Bot.]

1. Botany the primary or rudimentary leaf of the embryo of seed plants.
2. Anatomy any of several lobules of the placenta.

• Greek kotylēdó̄n a plant (probably navelwort), literally, a cuplike hollow, derivative of kotýlē cup
• Latin: navelwort
• 1535–45;

cot′y•le′don•al, cot•y•le•don•ar•y  (kot′l ēd′n er′ē), cot′y•le′don•ous, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

cotyledon / ˌkɒtɪˈliːd^ən/ noun

1. a simple embryonic leaf in seed-bearing plants, which, in some species, forms the first green leaf after germination

Etymology: 16th Century: from Latin: a plant, navelwort, from Greek kotulēdōn, from kotulē cup, hollow

ˌcotyˈledonal adjective

ˌcotyˈledonous, ˌcotyˈledoˌnoid adjective