未 成 熟(みせいじゅく)

みせいじゅく

noun, na-adjective

immature; unripe; not fully developed

formal

1. immature; unripe; not fully developed; not yet mature

The state of not having reached full maturity or development. Used for both physical immaturity (fruit, organisms) and abstract immaturity (skills, systems, markets, personality).

未成熟(みせいじゅく)な果実(かじつ)は酸(す)っぱい。

Unripe fruit is sour.

この市場(しじょう)はまだ未成熟(みせいじゅく)で伸(の)びしろがある。

This market is still immature and has room for growth.

若(わか)くて未成熟(みせいじゅく)な頃(ころ)の失敗(しっぱい)から多(おお)くのことを学(まな)んだ。

I learned a lot from the mistakes I made in my young, immature days.

技術(ぎじゅつ)はまだ未成熟(みせいじゅく)だが、将来性(しょうらいせい)は高(たか)いと評価(ひょうか)されている。

The technology is still immature, but it is rated as having high potential.

Composed of 未(み) (not yet) + 成熟(せいじゅく) (maturity, ripeness). The prefix 未(み) indicates that the state has not yet been reached, implying it may be reached in the future. This is different from 不(ふ), which negates more absolutely.

Common collocations

未成熟(みせいじゅく)な市場(しじょう): an immature market
未成熟(みせいじゅく)な技術(ぎじゅつ): immature technology
未成熟(みせいじゅく)な段階(だんかい): an immature stage
精神的(せいしんてき)に未成熟(みせいじゅく): emotionally immature

Related words

未(み)～ as a prefix meaning 'not yet':

未完成(みかんせい): incomplete, unfinished
未経験(みけいけん): inexperienced
未確認(みかくにん): unconfirmed

Similar words

成熟(せいじゅく): mature, ripe — the opposite; having reached full development
未熟(みじゅく): immature, unskilled — more common in everyday use; often implies lack of skill
幼稚(ようち): childish, infantile — more negative; implies thinking or behavior is inappropriately childlike

Related Words

Compare: 未熟(みじゅく) (immature, unskilled)

Compare: 幼稚(ようち) (childish, infantile)

Related: 未完成(みかんせい) (incomplete, unfinished)

Related: 未経験(みけいけん) (inexperienced)

Related: 未確認(みかくにん) (unconfirmed)

general

Added 2026.5.6 21:25 · Revised 2026.10.4 4:17

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