Definition of id est in English:

id est

noun

  • Used to introduce an explanation of a word or phrase: that is to say.

Origin

Old English; earliest use found in Bede's Ecclesiastical History. From classical Latin id est ‘that is’, used in works written in Latin to introduce an explanation of a word or phrase, ‘that is to say’ from id it + est, 3rd singular present indicative of esse to be.

Pronunciation

id est

/(ˌ)ɪd ˈɛst/