/ˌkɒtɪˈli:dn ||; ˌkɑtḷˈidṇ/noun [C] a part inside a seed that looks like a small leaf, which the developing plant uses as a store of food. Cotyledons are the first parts of the seed to appear above the ground when it begins to grow. 子叶（位于种子内部，形似小叶子，种子发芽时首先露出地面）