GNASH'ING, participle present tense nash'ing. Striking the teeth together, as in anger, rage or pain. GNASH'ING, noun nash'ing. A grinding or striking of the teeth in rage or anguish. There shall be weeping and gnashing of teeth. Matthew 8:12.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI