Gnash nash (charaq; brugmos): "Gnash" is used of grinding or striking together the teeth in rage, pain or misery of disappointment. In the Old Testament it is the translation of charak, a mimetic word, and represents for the most part rage, anger, hatred (Job 16:9, "He gnasheth upon me with his teeth," the Revised Version (British and American) "hath gnashed upon me"; Psalms 35:16, Psalms 37:12, Psalms 112:10, grief; Lamentations 2:16, contempt or derision); brucho, "to gnash the teeth in rage," indicates anger, rage, Septuagint for charaq (Acts 7:54, of Stephen, "They gnashed on him with their teeth"). The several instances of brugmos, "gnashing," in the Gospels seem to express disappointment rather than anger (Matthew 8:12,"There shall be wailing and gnashing of teeth," the Revised Version (British and American) "the weeping and the gnashing of teeth"; Matthew 13:42, Matthew 13:50, Matthew 22:13, Matthew 24:51, Matthew 25:30, Luke 13:28-a vivid representation of the misery of disappointed expectations; compare Ecclesiastes 30:10, "lest thou shalt gnash thy teeth in the end," gomphiazo, "to have the teeth set on edge"); trizo (Mark 9:18), which means "to give out a creaking, grating sound," "to screak," is used in the New Testament (in the above instance only) to mean "to grate or gnash with the teeth," indicating the effect of a paroxysm, the Revised Version (British and American) "grindeth his teeth."
W. L. Walker