The word mandible was first used in an early fifteenth century surgical guide, and was directly taken from the Latin word mandibula, meaning "jaw". That comes from the verb mandere, meaning "to chew", and finally derives from the Proto-Indo-European reconstruction mendh, also meaning "chew". This same root also went into Ancient Greek as mastax, or "jaw", into Medieval Greek as moustakion, into Italian as mostaccio, and became the word moustache that we use today (this is mostly spelled mustache in American English because of Merriam Webster and other dictionaries propagating a less French-looking spelling). At the same time, mendh additionally developed into another Latin verb for "chew", masticare, which eventually made its way into English as masticate. It's so cool that these words all share the same origin!
Hello! I'm Adam Aleksic, a sophomore studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy politics, vexillology, geography, board games, conlanging, and law.