The word "ridesup" is a verb that describes the action of a piece of clothing, usually underwear, shifting or moving upwards and becoming uncomfortable. It often refers to the feeling of underwear riding up and causing discomfort or irritation.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Becomes uncomfortable, in a way, as underwear. Explanations are generated by AI and may be inaccurate.