~なしに (without)

The compact adverbial form of なし ('absence') meaning 'without X' — 無し ('lacking') + に. Used with abstract nouns: 予告なしに ('without warning'), 断りなしに ('without permission'), 許可なしに ('without permission'). Slightly more literary than ~ないで or ~ずに for verbal actions. Compare なしで, which leans toward 'without using' while なしに leans toward 'in the absence of.'