Lexical Definition

‎τρίζω‎ trízō (trid'-zo) to gnash ^G:V
apparently a primary verb

gnash.

• to creak (squeak), i.e. (by analogy) to grate the teeth (in frenzy)

Abbott-Smith

** τρίζω [in Aq.: Am 2:13; Sm.: Is 38:14 * ;]
1. prop., of sounds by animals, to cry, chirp, etc.
2. Of other sounds, e.g., trans., τ. ὀδόντας, to gnash or grind the teeth: Mk 9:18.†

Abbott-Smith References

Liddell-Scott-Jones

τρίζω,

[Refs 8th c.BC+]; but perfect τέτριγα is more frequently in present sense, Epic dialect participle τετριγῶτες, for τετριγότες, [Refs 8th c.BC+] —properly of sounds uttered by animals (compare τριγμός, τρύζω), utter a shrill cry, of young birds, [Refs 8th c.BC+]; of bats, [Refs 8th c.BC+]; of the Τρωγοδύται, τετρίγασι κατά περ αἱ νυκτερίδες [Refs]; of partridges, [Refs 4th c.BC+]; of the ἴυγξ,[Refs]; of locusts, [Refs]; of young swallows, [Refs 2nd c.AD+]; of the elephant, [Refs]; of mice, [Refs 4th c.BC+]; of the fish called σελάχη, [Refs 4th c.BC+]: also applied to the noise made by ghosts, 'squeak and gibber', [Refs 8th c.BC+]; ἔτριζον δίκην ἀσπίδων (αἱ ψυχαί) [Refs 2nd c.AD+]

__2 of other sounds, τετρίγει (Epic dialect pluperfect) δ᾽ ἄρα νῶτα θρασειάων ἀπὸ χειρῶν the wrestlers' backs creaked, [Refs 8th c.BC+]; so τρίζει, crepitates, of a broken collar-bone, [Refs 2nd c.AD+]grinds, [Refs 5th c.BC+]; τὸ τρίζειν ἀκουσίως involuntary gnashing, [NT+2nd c.AD+]; of a musical string, give a crack, [Refs]; of an axle, creak, ἄξων τετριγὼς ὑπ᾽ ἄμαξαν [Refs 3rd c.BC+]; so of a cart-wheel, [Refs 2nd c.AD+]; of a shoe, [Refs 2nd c.AD+]; ἡ κοιλίη τ. [Refs 5th c.BC+]; of singing in the ears, τὰ ὦτα τέτριγε [Refs]; of the hissing or crackling of a person burnt in the fire, [Refs 5th c.BC+]

_{LSJ Scripture Refs: Mark.9.18}