noun
hacking to pieces; slashing wildly
Describes cutting something into many pieces in a violent, reckless, or indiscriminate manner. Often used figuratively for harsh criticism or thorough destruction.
犯人は被害者をメッタ斬りにした。
The culprit hacked the victim to pieces.
彼の新作は評論家にメッタ斬りにされた。
His new work was torn to pieces by the critics.
ずたずた is an adverb meaning 'to shreds' or 'in tatters', often used with 切る or 裂く. メッタ斬り emphasizes the violent, reckless action of cutting, while ずたずた focuses on the resulting state of being cut into many pieces.
Compound of 滅多 (metta, 'reckless, indiscriminate') and 斬り (kiri, 'cutting'). The exact origin of 滅多 is uncertain, but it may be related to the Buddhist term 滅度 (metsudo, 'nirvana') or a shift from 目出度 (medetai, 'auspicious').