同一

• Pinyin: tóng yī
• Hanzi breakdown: 同 = 冂 (enclosure) + 口 (mouth) + 一; 一 = single horizontal stroke representing 'one'

Meaning

Same; identical; one and the same. Emphasizes that two or more things are exactly the same entity or belong to the same category.

Used as an attributive modifier before nouns. Stronger than 相同 (similar/same) — 同一 emphasizes identity or singularity, while 相同 can mean merely similar. Often appears in formal or analytical contexts.

Examples

1. 这两起案件的作案手法完全一样，可能是同一个人干的。 The methods used in these two cases are exactly the same; it might be the same person.
2. 我们住在同一栋楼，但以前从来没见过面。 We live in the same building, but we've never met before.
3. 科学家发现这两种疾病其实是由同一种病毒引起的。 Scientists discovered that these two diseases are actually caused by the same virus.

Usage Guide

Context: analytical, descriptive, academic

Tone: precise

Do Say

• 他们在同一所学校读书。(They study at the same school.)
• 这两个概念不能混为同一。(These two concepts cannot be conflated as one.)

Don't Say

• 我们的想法同一 — 作形容词时要加'的'，说'我们的想法是同一的'或更自然地说'我们的想法一样'

Origin & History

Compound of 同 (same) + 一 (one). Literally 'same one,' emphasizing singularity and identity rather than mere similarity.

Cultural Context

Generation: All ages

Social background: Universal