What is a structured settlement?

An "unstructured settlement" is referred to as a "lump sum".

Usually if someone wins some form of monetary compensation in a lawsuit the money is paid out in one of two ways - they get a lump sum payment for the full amount or an amount of money is deposited in an account somewhere and payments are made from that account on a recurring basis. (Usually monthly or annually) like an annuity.

That 2nd type of arrangement is a "structured settlement".