Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
MORDAUNT
As described in historical dictionaries
Patronymica Britannica (1860)
MORDAUNT. Accordincr to the senealogy of this family, printed temp. Charles II., their patriarch was Sir Osbert le Mordaunt, who possessed Kadwell, co. Bedford, by the gift of his brother, who had received it from the Conqueror, for services rendered by himself and his father. Le Mordannt — " the Biter " — is evidently a sobriquet allusive to some feat performed with the teeth.
Origin: English
Region of origin: British Isles
Country of origin: England
Religion of origin: Christian
Language of origin: English