a heavy iron ball fastened by a chain to a prisoner's leg.
a burdensome restraint: The steady accumulation of small debts was a ball and chain to his progress.
FacetiousSlang: Often Offensive. a person's spouse or romantic partner, especially a female.
Origin of ball and chain
An Americanism dating back to 1825–35
In the meaning “romantic partner,” this term is consciously used for humorous or playful effect. But it is often perceived as insulting, implying that the partner is a burden or restriction on the other partner.
A burden and restraint, as in Karen regarded her job as a ball and chain, but she needed the money. The term, dating from the early 1800s, alludes to chaining a heavy iron ball to a prisoner's leg. Later it was transferred to other kinds of restraining burden.