knock on wood

knock on wood idiom
Also, touch wood. Express a wish that something will or will not occur, as in This last round of treatment should have cured her, knock on wood. This expression alludes to an ancient superstition that literally knocking on or touching wood will ward off evil spirits. [c. 1900]

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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