But it's superfluous, really-which is why calling someone a "fifth wheel" is a way of calling them unnecessary, basically a tagalong.
I don't have a role in the office anymore-i feel like a fifth wheel.
When I was young, I always thought that I was the fifth wheel both at home and school, but when I saw the sunshine, I saw hope.
All the boys and girls were dancing at the party while I sat at a table alone, feeling like a fifth wheel.
By definition, a fifth wheel is a wheel or a portion of a wheel with two parts rotating on each other that sits on the front axle of a carriage and adds extra support so it doesn't tip.
If someone is a fifth wheel, they may feel like an unimportant part of a group, usually a group of couples.
A mother-in-law on a honeymoon is a fifth wheel.
The fifth wheel provides a solid connection point to carry the bracket quickly.