noun
scatterbrain; absent-minded person; careless person
Describes someone who is habitually forgetful, inattentive, or makes careless mistakes.
彼は慌て者で、よく財布を忘れる。
He's a scatterbrain and often forgets his wallet.
noun
Refers to someone who acts impulsively or rushes into things without thinking.
慌て者はすぐに決断して後悔することが多い。
Rash people often make quick decisions and regret them later.
Compound of 慌て (awate, 'to panic, be flustered') + 者 (mono, 'person'). The exact historical derivation is uncertain, but the meaning is transparent from its components.