μάρτυς

Etymology
Often assigned to, which is acknowledged by Beekes, but he finds it unconvincing and instead derives it from  based on the ending of the word. Compare 🇨🇬 and 🇨🇬.

Le Feuvre (2021) maintains the usual derivation from and explains the ending of the word from a zero-grade of, whence also.

Noun

 * 1) witness
 * 2) martyr

Related terms
and see words with μαρτυρ-, μάρτυς @perseus.tufts.edu