亦即

yìjí

conjunction

Meanings

HSK 5

明天，亦即五月一日，是劳动节。

Míngtiān, yìjí wǔyuè yī rì, shì Láodòngjié.

Tomorrow, that is, May 1st, is Labor Day.

HSK 7-9

光速，亦即每秒约三十万公里，是宇宙中最快的速度。

Guāngsù, yìjí měi miǎo yuē sānshíwàn gōnglǐ, shì yǔzhòu zhōng zuì kuài de sùdù.

The speed of light - that is, about 300,000 km per second - is the fastest speed in the universe.

Formal/written. In speech and casual writing use 也就是 (yě jiùshì) instead. 亦即 belongs to academic papers, legal documents, and reference works.

memory

亦 (also) + 即 (namely/that is) - a classical doublet. The 亦 was the literary 'also/likewise' (= modern 也), so 亦即 is just the formal cousin of 也就是.

亦 yì

即 jí