Dicotyledon
in the singular, a plant having two cotyledons or seedleaves, that is, primordial leaves, contained in the embryo. The majority of flowering plants have this structure.
When therefore seed is sown, in most cases the future plant first appears above the ground as a tiny two-leaved existence, and in certain cases the next pair of leaves which appear, and all the future ones, are of a different structure from the first. The primordial pair of leaves are the two cotyledons. Th Their use in the economy of nature is to shelter the ordinary leaves situated inside. In the plural the highest class of the vegetable kingdom, containing orders of plants with the structure of seed just described.