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.
Facetious Slang: Often Offensive. a person's spouse or romantic partner, especially a female.
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.