primarily, "to bit or eat greedily" (akin to bruko, "to chew"), denotes "to grind or gnash with the teeth," Acts 7:54 .
primarily used of the sounds of animals, "to chirp, cry, squeak," came to signify "to grind or gnash with the teeth," Mark 9:18 .
akin to A, No. 1, denotes "gnashing" ("of teeth" being added), Matthew 8:12; 13:42,50; 22:13; 24:51; 25:30; Luke 13:28 .