What does "per stirpes" mean?

The phrase "per stirpes" is a Latin term which means "by roots." It is a legal term used to describe the way in which an estate is divided among a beneficiary's children if that beneficiary dies before the benefactor who made the will.

If an estate is to be divided per stirpes, a deceased beneficiary's share of the estate is divided equally among his children. For example, if the benefactor of a will has two heirs, each with two children of their own, and one of the heirs dies before he does, the living beneficiary receives half the estate while the two children of the deceased beneficiary each receive one quarter.