fifth wheel

English Thesaurus

1. a steering bearing that enables the front axle of a horse-drawn wagon to rotate (noun.artifact)

hypernym	:	bearing,
definition	:	a rotating support placed between moving parts to allow them to move easily (noun.artifact)

2. an extra car wheel and tire for a four-wheel vehicle (noun.artifact)

hypernym	:	car wheel,
definition	:	a wheel that has a tire and rim and hubcap; used to propel the car (noun.artifact)

3. someone or something that is unwanted and unneeded (noun.attribute)

hypernym	:	redundance, redundancy,
definition	:	the attribute of being superfluous and unneeded (noun.attribute)