When reading Jane Austen's Pride and Prejudice, what does entailment mean?

Entailment is a system of inheritance that limits the inheritance to specific heirs; that is, only certain people can receive the inheritance. In Jane Austen's Pride and Prejudice, owning land boosted a family's status and income. An entail helped keep all of the land in one chunk and in one family (on the male side) through the generations. The eldest son stood to inherit the bulk of an estate.

In Pride and Prejudice, the Bennets had only daughters, so the entailment was broadened to include the closest male relative. In this case, Mr. Collins (a distant cousin of Mr. Bennet) came up the winner.

Because of the entailment, Mrs. Bennet was justifiably desperate to get her daughters married — and the wealthier the better. Acceptable employment opportunities were extremely limited for women in their social class, so the Bennet women faced destitution after Mr. Bennet's death. There were only two ways for the young women to avoid this fate: charity from relatives or marrying a rich guy.