Precocious

Webster's Dictionary of the English Language

·adj Ripe or mature before the proper or natural time; early or prematurely ripe or developed; as, precocious trees.

II. Precocious ·adj Developed more than is natural or usual at a given age; exceeding what is to be expected of one's years; too forward;

— used especially of mental forwardness; as, a precocious child; precocious talents.