숙성해요 · 숙성했어요 · 숙성한 (+noun)
mature beyond one's years, precocious
Example
그 아이는 나이에 비해 생각이 무척 숙성해요.
That child thinks in a very mature way for her age.
Word parts
숙 early+성 complete
Literally 'early-completed'.
Good to know
Homonym: 숙성 'aging, fermenting', as in 숙성된 김치 or 고기, is far more common.
Related words