To miss (an opportunity); to let something get away; to lose a chance or fail to catch something.
大事なプレゼンの機会を逃してしまった。
I missed an important presentation opportunity.
決定的な瞬間にボールを逃してしまった。
He missed the ball at a decisive moment.
その株は買うチャンスを逃すと二度と戻らないかもしれない。
If you miss the chance to buy that stock, it may never come back.
To set free; to let go and allow something or someone to escape.
網にかかった魚を海に逃がした。
I released the fish caught in the net back into the sea.
警察は容疑者を取り逃がしてしまった。
The police let the suspect get away.
An auxiliary use attached to the -masu stem of a verb to mean 'fail to do ~' or 'miss doing ~' (e.g., 予約し逃す = fail to make a reservation).
人気の公演のチケットを買い逃すと入れないかもしれない。
If you fail to buy tickets for the popular performance, you might not get in.
予約し逃すと、別の日程を探さなければならない。
If you fail to make a reservation, you'll have to look for another date.