precocious

Now those abominations whom you call precocious boys—your little pet monsters, doctor!—and who can wonder that the world is what it is? when it is full of them—as they will have no…

The precocious plant was already blooming flowers by day 4.

Mary: Even though the sound of it is something quite atrocious / If you say it loud enough you'll always sound precocious.

The precocious child began reading the newspaper at age four.