E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A right of the lord of a manor to the best jewel, beast, or chattel of a deceased copyhold tenant. The word is compounded of the Saxon here (army), geatu (grant), because originally it was military furniture, such as armour, arms, and horses paid to the lord of the fee. (Canute, c. 69.)