How to say "hacking" in Japanese

• 侵入しんにゅうJLPT N2approx.Common
  noun, suru verb, intransitive verbHacking as the act of breaking into a computer or network — the intrusion itself, not the techniques. It also means an invasion or raid, so context must show a computer is meant.
  「ピッキングの道具どうぐ無なしで、どうやって侵入しんにゅうした？」「トイレの窓まどがあいた」↗

  "With no picks how did you break in?" "The toilet window was open."
• ハッキング
  nounThe straightforward loanword for hacking as an activity, covering the sense of breaking into computers. A safe choice in general talk and writing about hacking.
• 不正アクセスふせいアクセス
  nounUnauthorized access to a computer system — hacking framed as an offense. The term you meet in legal and news contexts, stressing that the access was not permitted.

Use 「ハッキング」 for hacking as a general activity, 「不正アクセス」 for hacking as unauthorized access in legal or official contexts, and 侵入 for the act of breaking into a system.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 侵入しんにゅうinvasion
• ハッキングhacking
• 不正アクセスふせいアクセスunauthorized (computer) access