third wheel(redirected from 3rd)
Also found in: Dictionary, Thesaurus, Wikipedia.
Someone who has no real place or purpose in a situation, likened to a superfluous extra wheel on a two-wheeled vehicle. When Kelly invited me to go to the movies, I didn't know that her boyfriend would be joining us. I felt like a third wheel the entire night.
n. an extra person; a person who gets in the way. (see also spare tire.) Well, let’s face it. We don’t need you. You are a third wheel.