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.