v. t. [ imp. & p. p. Gnashed p. pr. & vb. n. Gnashing. ] [ OE. gnasten, gnaisten, cf. Icel. gnastan a gnashing, gn&unr_;sta to gnash, Dan.knaske, Sw. gnissla, D. knarsen, G. knirschen. ] To strike together, as in anger or pain; as, to gnash the teeth. [ 1913 Webster ]