gnash one's teeth

gnash one's teeth idiom
Express a strong emotion, usually rage, as in When Jonah found out he was not going to be promoted, he gnashed his teeth. This expression is actually redundant, since gnash means “to strike the teeth together.” Edmund Spenser used it in The Faerie Queene (1590): “And both did gnash their teeth.” [Late 1500s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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