同一

どういつ

identity, sameness, similarity

JLPT N3

Character Breakdown

Meaning and Usage

The term 同一 (tóngyī) means 'the same' or 'identical.' It is used to emphasize that two or more things share the exact same identity or characteristic. It often appears before nouns to indicate sameness.

Common Contexts

It is frequently used in everyday conversation to describe objects, people, places, or abstract concepts that are identical or unified. For example, 同一衣服 (the same piece of clothing) or 同一学校 (the same school).

Collocations and Patterns

  • 同一 + noun: emphasizes that the noun is exactly the same.
  • 同一时间 (the same time): used to indicate simultaneity.
  • 同一问题 (the same problem): used to express identical issues.

Usage Notes

同一 is more formal and precise than just using (same). It stresses exact identity rather than similarity. Avoid confusing 同一 with 类似 (similar) or 相同 (similar but not necessarily identical). 同一 implies complete identity.

Summary

Use 同一 when you want to clearly state that two or more things are exactly the same in identity or nature, especially in formal or written contexts.

Example Sentences

They are wearing the same piece of clothing.

We come from the same school.

The answers to these two questions are the same.