na-adjective, noun
reckless; rash; foolhardy; daredevil
Describes a person or action that is heedless of danger or consequences, often with a nuance of boldness or daring. Can be used both negatively (foolhardy) and positively (daring).
彼の向こう見ずな運転にはいつもひやひやする。
His reckless driving always makes me nervous.
向こう見ずな挑戦だった
It was a foolhardy challenge, but it succeeded.
無謀 is more formal and emphasizes lack of planning or thought, while 向こう見ず is more colloquial and focuses on ignoring danger.
がむしゃら implies reckless determination and single-minded effort, often in a positive light, whereas 向こう見ず can be purely about risk-taking without the same nuance of effort.
Compound of 向こう (mukō, 'the other side, beyond') + 見ず (mizu, 'not seeing', from 見る). Literally 'not seeing what lies ahead', hence 'reckless'.