Are yams and sweet potatoes the same?
1640s, "developed before the usual time" (of plants), with -ous + Latin praecox (genitive praecocis) "maturing early," from prae "before" (see pre-) + coquere "to ripen," literally "to cook" (see cook (n.)). Originally of flowers or fruits. Figurative use, of persons, dates from 1670s. Related: Precociously; precociousness.
precocious pre·co·cious (prĭ-kō'shəs)
Showing unusually early development or maturity.