gnash

动词 gnash:

1. grind together, of teeth

1. I was gnashing my teeth with rage.
   我咬牙切齿愤怒已极。

gnash

v.tr.（及物动词）
gnashed,gnash.ing,gnash.es
To grind or strike (the teeth, for example) together.
咬，啮（如牙齿）
To bite (something) by grinding the teeth.
啮咬（某物）

来源：
Alteration of Middle English gnasten, gnaisten [possibly of Scandinavian origin] ; akin to Old Norse gnastan [a gnashing]
中古英语 gnasten的变化, gnaisten [可能源于古斯堪的纳维亚语] ；类似于 古斯堪的纳维亚语 gnastan [咬]

【引伸】
gnash
n.（名词）