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unsatisfied; unsatisfactory; insufficient in some way; lacking something
一人前の量ではこの食べ盛りの子供には物足りないと感じた。
I felt this amount was unsatisfying.
説明が簡単すぎて物足りなかった。
The explanation was too simple and left me unsatisfied.
何か物足りないと思ったら塩が足りない。
When I felt something was missing, it turned out salt was lacking.