- 同一个 tóngyīgè the samereferring to one and the same person or entity, used to express identity or lack thereof.
- 同一个世界，同一个梦想 tóngyīgèshìjiè, tóngyīgèmèngxiǎng Olympic mottoOne world - one dream, motto of 2008 Beijing Olympic games
- 同一屋檐下 tóngyīwūyánxià under the same roofsharing the same living space or dwelling
- 同一挂 tóngyīguà aliketo have a lot in common with someone or be of the same type or category
- 同一码子 tóngyīmǎzi the same thingidiomatic expression meaning the same thing or of the same nature, often used in negative or comparative contexts.
- 性同一性障碍 xìngtóngyīxìngzhàng'ài gender identity disorder
