adverb
deliberately; intentionally; on purpose
Used when someone does something knowingly and willfully, often with a negative implication. Synonymous with わざと, but 故意に is more formal and often used in legal or serious contexts.
See also: 故意 (こい)
彼は故意に私の質問を無視した。
He deliberately ignored my question.
故意に法律を破る行為は許されない。
Deliberately breaking the law is unacceptable.
Compound of 故 (ko, 'reason, cause') and 意 (i, 'mind, thought'), with the adverbial particle に. The meaning 'deliberately' arises from the idea of acting with a conscious reason or intent.