青二才(あおにさい)

A somewhat old-fashioned but still understood word. 青(あお) (blue/green) carries connotations of immaturity in Japanese (as in 青臭(あおくさ)い, green/immature), and 二才(にさい) is an archaic word for a young person. The word is usually used by older people to dismiss younger ones, or self-deprecatingly when reflecting on one's own past.

Common collocations

• 青二才(あおにさい)のくせに: despite being a greenhorn
• 青二才(あおにさい)が偉(えら)そうに: a greenhorn acting important
• まだ青二才(あおにさい)だ: still just a greenhorn

Similar words

• 世間知(せけんし)らず: naive, unworldly — focuses on lack of social awareness, while 青二才(あおにさい) emphasizes youthful arrogance or presumption
• 若造(わかぞう): young upstart — similarly dismissive of youth, but less literary
• 半人前(はんにんまえ): half-fledged — focuses on incomplete skill development rather than attitude