一斉

いっせい

simultaneous, all at once

JLPT N2

Character Breakdown

Meaning and Usage

"一斉" (いっせい) means "simultaneous" or "all at once." It is used to describe actions or events happening together at the same time by multiple people or things.

Common Contexts

You often see "一斉に" followed by verbs like "始める" (to start), "動く" (to move), or "叫ぶ" (to shout), emphasizing that everyone or everything acts simultaneously.

Collocations and Patterns

  • 一斉に + verb (e.g., 一斉に走る): to do something all at once
  • 一斉に動く: to move simultaneously
  • 一斉に質問する: to ask questions all at once

Register and Nuance

"一斉" is neutral and can be used in both formal and informal contexts. It often appears in news reports, instructions, or descriptions of group actions.

Common Mistakes

Learners sometimes confuse "一斉" with "同時" (どうじ), which also means "simultaneous." The difference is that "一斉" emphasizes a coordinated or collective action happening all at once, while "同時" simply means at the same time without implying coordination.

Example Sentences

こどもたちはせんせいのあいずでいっせいにはしりだした。

The children started running all at once at the teacher's signal.

いっせいにしつもんがとびかい、かいぎはかっきづいた。

Questions flew simultaneously, and the meeting became lively.

じしんのけいほうがなると、いっせいにみんながひなんをはじめた。

When the earthquake alarm sounded, everyone started evacuating at once.