the first single leaf or one of the first pair of leaves produced by the embryo of a flowering plant, or any of various similar structures found in conifers
Botany A leaf of the embryo of a seed plant, which upon germination either remains in the seed or emerges, enlarges, and becomes green. Also called seed leaf.
Anatomy One of the lobules constituting the uterine side of the mammalian placenta, consisting mainly of a rounded mass of villi.