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gentle; quiet; mild; meek; obedient; docile; well-behaved; tame
quiet (color, pattern, etc.); sober
彼の子供はとても大人しいよね。
His child is very quiet.
大人しくしていれば問題ないよ。
If you stay quiet, there's no problem.
犬は大人しいけど猫は活発だね。
The dog is docile but the cat is active.