一回事

• Pinyin: yī huí shì
• Hanzi breakdown: 一 = one; 回 = 口 within 囗 (whirlpool — a round, an occurrence, an instance); 事 = 史 (record/handle — an affair, a matter)

Meaning

One and the same thing; the same matter. Used in contrastive patterns to assert that two things are identical — or, far more commonly, to assert that they are entirely different matters.

Most frequently appears in contrastive structures: 是一回事 (is the same thing), 不是一回事 (is not the same thing at all), 是另一回事 (is quite another matter). A rhetorical device to draw sharp distinctions between things that might appear similar. Very common in spoken and formal written Chinese. Informal to neutral in register.

Examples

1. 知道该怎么做是一回事，真正动手去做又是另一回事，中间的差距往往需要持续行动才能填补。 Knowing what to do is one thing; actually doing it is another. The gap in between often takes sustained action to close.
2. 销售额提高是一回事，利润率是否同步提升则完全是另一回事，两者不可混淆。 Higher sales are one thing; whether profit margins rise at the same time is a completely different matter. The two shouldn’t be confused.
3. 他说支持改革是一回事，但他在董事会上的实际投票行为则是完全不同的一回事。 He says he supports reform—that’s one thing. But how he actually votes on the board is an entirely different matter.

Usage Guide

Context: argument, clarification, daily life, rhetoric

Tone: neutral

Do Say

• 法律上是否侵权是一回事，商业道德上是否妥当是另一回事，二者不能混为一谈。(Whether something is infringement in law is one matter, and whether it is proper in business ethics is another, and the two cannot be confused.)
• 懂语法是一回事，能在自然环境里流利运用是另一回事，必须靠大量输入和练习。(Knowing grammar is one matter, and being able to use it fluently in a natural setting is another; it requires plenty of input and practice.)

Don't Say

• 我要一回事苹果 — 一回事 is a noun/predicate phrase, not a measure word; use 一个 for countable nouns; 一回事 cannot replace quantity expressions

Origin & History

一 (one/a single) + 回 (time/occasion — 口 within 囗, originally depicting a whirlpool; extended to a round or occurrence) + 事 (matter/affair — 史 history/record; a matter that is handled)

Cultural Context

Era: Modern

Generation: All ages

Social background: Universal