happening or existing by chance

Reports suggest that eleven soldiers were killed by accidental fire from their own side. 报道暗示11名士兵被己方炮火误射而丧生。

The site was located after the accidental discovery of bones in a field. 有人在田地里意外地发现遗骨后，这个遗址才被发现。

He plays a naive salesman who becomes an accidental hero by saving a child's life.

a sign showing that there is a temporary change from the key signature (= the set of musical notes that should normally be played for a particular piece of music)

a bird that is found in a place where birds of its type are not usually found

You may spot accidentals driven in by the stormy weather. 你可能会观察到一些鸟因为恶劣天气而被迫飞到它们通常不会出现的地方。