fifth wheel—said of a person or thing that is superfluous or needless:
- Look guys, I don’t know what’s going on, but I feel like a fifth wheel here. I should go.
Note: The expression does not correlate in meaning with the phrase fifth quarter—
1. the summer quarter of studies:
- In the fifth quarter the student is encouraged to take no more than one course besides the four hours of thesis.
2. (dated butcher’s term) the hide and fat of a slaughtered animal:
- He claimed, and obtained the fifth quarter of the beef, as it is called (the hide and tallow) for his forbearance.
third wheel—a third person to accompany a couple (with the implication that one is intruding on a couple):
- I find it tiring to be the third wheel, having to constantly walk behind a couple holding hand.
Note: The expression does not correlate in meaning with the phrase third rail—(U.S. coll.) a subject considered by politicians to be too controversial or dangerous to discuss:
- The conventional wisdom has long been that Social Security is the third rail of American politics.