at the back of something, often hidden
The sun was hidden behind the clouds.
太陽は雲の後ろに隠れていた。
falling short of progress or schedule
We're behind schedule because of the delay.
遅れのために、予定に遅れています。
supporting or approving of someone or something
Her family was right behind her decision.
彼女の家族は彼女の決定を完全に支持していた。
responsible for the creation or development of something
She was the mastermind behind the successful project.
彼女は成功したプロジェクトの背後にある策略家でした。
in the past, no longer a concern
The mistake is behind you, don't dwell on it.
失敗はもう過去のことですから、気にしないでください。
further back or at the back
She walked behind the line of trees.
彼女は木々の列の後ろを歩いた。
remaining in a place after others have left
Her keys were left behind on the table.
彼女の鍵はテーブルに忘れてしまった。
later than the due date or expected time
He is behind in his payments.
彼は支払いが遅れています。
a polite way to refer to someone's buttocks
He sat down hard on a rock and hurt his behind.
彼は岩に激しく座り、お尻を痛めた。