thumb (one's) nose at (someone or something)
1. Literally, to perform a rude gesture in which one touches their nose with their thumb in order to express contempt or a lack of respect. Did that guy really just thumb his nose at me? Do people still do that?
2. To openly display contempt or an intentional lack of respect toward someone or something. Don't thumb your nose at the boss if you want to keep your job!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
thumb (one's) nose
To express scorn or ridicule, often by placing the thumb on the nose and wiggling the fingers.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.