What is Allodium?

Legal Definition
Estates. Signifies an absolute estate of inheritance, in coutradistinction to a feud.

2. In this country the title to land is essentially allodial, and every tenant in fee simple has an absolute and perfect title, yet in technical language his estate is called an estate in fee simple, and the tenure free and common socage. 3 Kent, Com. 390; Cruise, Prel. Dis. c. 1, 13; 2 Bl. Com. 45. For the etymology of this word, vide 3 Kent Com. 398 note; 2 Bouv. Inst. n. 1692.
-- Bouviers Law Dictionary
Legal Definition
Land held absolutely In one's own right, and not of any lord or superior; land not subject to feudal duties or burdens. An estate held by absolute ownership, Without recognizing any superior to whom any duty is due on account thereof. 1 Washb. Real Prop. 16. McCartee v. Orphan Asylum, 9 Cow. (N. Y.) 511, 18 Am. Dee, 516.
-- Black's Law Dictionary
Legal Definition
An allodial estate; one not held under a superior.
-- Ballentine's Law Dictionary