thumb (one's) nose
To express scorn or ridicule by or as if by placing the thumb on the nose and wiggling the fingers

[TahlilGaran] Dictionary of Contemporary English ▲

thumb one's nose
v. phr.
1. To hold one's open hand in front of one's face with one's thumb pointed at one's nose as a sign of scorn or dislike.
After Bob ran into the house he thumbed his nose at Tom through the window.
2. informal To look with disfavor or dislike; regard with scorn; refuse to obey.
■ Used with "at".
Betty thumbed her nose at her mother's command to stay home.
Mary thumbed her nose at convention by wearing odd clothes.
Compare: LOOK DOWN ON.

[TahlilGaran] English Idioms Dictionary ▲