the mind > emotion > anger > manifestation of anger > show anger [verb (transitive)] > gnash or grind the teeth (6)
transitive. = gnash, v. 2.
transitive. To grind (the teeth). Obsolete.
transitive. To rub harshly together, ‘grind’ (the teeth).
transitive. To strike (the teeth) together, as in rage or anguish.
transitive. To strike together the eyelids (= bat, v.2), or the teeth; also intransitive either of a person, or his teeth (= chatter). Obsolete.
To grind or grate (the teeth).