闇討ち

1. Origins, structure, and basic meaning

• Structure: 闇討ち, read やみうち, combines darkness 闇 with attack 討ち to denote an ambush from concealment.
• Basic usage: It denotes attacking from concealment when the target is unprepared, as in 旅人を闇討ちする.

2. Common pitfalls and similar expressions

• Tone and register
  • It strongly suggests a cowardly or unfair method in contrast with a face-to-face contest 正面勝負.