rabbi

English borrowed rabbi through Middle English raby, from Ecclesiastical Latin rabbi, which came from Koine Greek ῥαββί, itself from post-Tanakh Hebrew רַבִּי, literally 'my master' — built from רַב (rav, 'master') plus the possessive suffix ־ִי ('my').

The word entered English as early as late Old English (rabbi) and settled into Middle English as raby, moving from Hebrew through Greek and Latin without shedding its core meaning of a respected master.

It's a doublet of rebbe, meaning the two words descend from the same Hebrew root but arrived in English by different paths, and it's related to rav, the underlying Hebrew word for 'master.'