E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The word means one bound, a bondsman (Latin, ligo, to bind); hence, vassals were called liege-meni.e. men bound to serve their lord. The lord was called the liege-lord, being bound to protect the vassals.
Unarmed and bareheaded, on his knees, and with his hands placed between those of his lord, he [the military tenant] repeated these words: Hear, my lord, I have become your liegeman of life and limb, and earthly worship; and faith and truth I will bear to you to live and die.Lingard: History of England, vol. ii. chap. i. p. 27.