brux·ism 
(brŭksĭz′əm)
(brŭksĭz′əm)n.
The habitual, involuntary grinding or clenching of the teeth, usually during sleep.
[From New Latin brūxis, a gnashing, from Greek brūkein, to gnash.]
- unaneled
- unanimity
- unanimous
- unanimously
- unanimousness
- unannounced
- unanswerability
- unanswerable
- unanswerableness
- unanswerably
- unanticipated
- unanticipatedly
- unapologetic
- unapologetically
- unappealable
- unappealably
- unappealing
- unappealingly
- unappeasable
- unappeasably
- unappetizing
- unappetizingly
- unappreciated
- unappreciative
- unappreciatively