noun
random pounding; wild beating
Describes hitting or striking something in a wild, irregular, or random manner, often used for drumming or repeated striking actions.
太鼓の乱れ打ちが祭りの始まりを告げた。
The random pounding of drums announced the start of the festival.
Compound of 乱れ (midare, 'disorder, confusion') and 打ち (uchi, 'striking, hitting'). The exact historical derivation is uncertain, but the word straightforwardly describes disordered striking.