Adult

adult, full-grown, middle-aged, prime, grown, grown-up, of age, in full bloom, full-fledged, in one's prime, womanly, manly, matronly, older, developed, prepared, settled, sedate, experienced, seasoned, knowledgeable, sophisticated; see also experienced, matured, ripe 2.

Antonyms juvenile, young*, immature. *

Ripe

ready, seasoned, perfected; see mellow 1, ripe 1, 2.

Considered

thought about, reasoned, seasoned; see considered 1, thoughtful 1. See syn. study at ripe.

To come to maturity

grow up, become a man, become a woman, come of age, reach adulthood, become experienced, settle down, become full-blown, ripen into, ripen, reach perfection, become prime, attain majority, culminate, become wise, become perfected, grow skilled, fill out; see also age 1, develop 1.

To grow

ripen, mellow, evolve; see grow 2.