What is Bairn's Part?

Legal Definition
Scottish, law. Children's part a third part of the defunct's free movables, debts deducted, if the wife survive, and a half if there be no relict.
-- Bouviers Law Dictionary
Legal Definition
In Scotch law. Children's part; a third part of the defunct's free movables, debts deducted, If the wife survive, and a half if there be no relict.
-- Black's Law Dictionary
Legal Definition
(Scotch) A third of a decedent’s estate if there was a widow, half if not.
-- Ballentine's Law Dictionary