Strong’s Greek
G5149 — trizo
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
τρίζω
trizo — pronounced trid'-zo
apparently a primary verb; to creak (squeak), i.e. (by analogy) to grate the teeth (in frenzy):--gnash.
1 occurrence in the KJV.
Mark 9:18
And wheresoever he taketh him, he teareth him: and he foameth, and gnasheth with his teeth, and pineth away: and I spake to thy disciples that they should cast him out; and they could not.