一瞬

1. Origins, structure, and basic meaning

• Structure: 一瞬 is read as いっしゅん and is a noun and adverbial expression for an extremely brief instant.
• Basic usage: A light going out momentarily appears in 電気が一瞬消える, while a bird being visible for only an instant appears in 鳥が一瞬だけ見える.

2. Common pitfalls and similar expressions

• Emphasis with だけ
  • 一瞬だけ stresses that the sight or event was limited to that single brief instant.
• Difference from しばらく
  • Unlike a word for a short period that continues for some time, this term focuses on a nearly instantaneous moment.