[cot.y.le.don] n [NL, fr. Gk kotyledon cup-shaped hollow, fr. kotyle cup, anything hollow] (1540) 1: a lobule of the mammalian placenta
2: the first leaf or one of the first pair or whorl of leaves developed by the embryo of a seed plant or of some lower plants (as ferns)--see plumule illustration -- cot.y.le.don.ary adj