gnash 
/ˈnæʃ/ verb
gnash·es; gnashed; gnash·ing /ˈnæʃ/ verb Meaning:
gnash your teeth 1 : to grind your teeth together
▪ He gnashed his teeth in his sleep. 2 : to show you are angry, upset, etc.
▪ His opponents have been gnashing their teeth in/with frustration [=they have been showing their frustration] since he won the election. ▪ His election has caused some weeping and gnashing of teeth among his opponents.
▪ He gnashed his teeth in his sleep.
▪ His opponents have been gnashing their teeth in/with frustration [=they have been showing their frustration] since he won the election. ▪ His election has caused some weeping and gnashing of teeth among his opponents.
