An Etymological Dictionary of Astronomy and Astrophysics

1a) Silent; refraining from speech or utterance.

1b) Not emitting or having sound of any kind.

2a) To turn off (a microphone, a speaker, or audio.

2b) To muffle, reduce, or eliminate the sound of (Dictionary.com).

Etymology (EN): M.E. muet, mewet, muwet, from O.Fr. müet, muet “dumb, mute,” from L. mutus “silent, dumb,” ultimately from PIE imitative base *meue-; cf. Skt. mûka- “dumb;” Gk. mukos, mutis “dumb,” myein “to be shut” (of the mouth); Iranian Khotanese mutä “dumb.”

Etymology (PE): Xab, from Pers. xab “silent, mute,” variants xape, xafe, xabak, xabâk “choked, strangled.”