name of the cat in "Reynard the Fox" (late 15c.), hence used as a proper name for any cat, from Flemish and Dutch Tybert, Old French Tibert. Identified by Shakespeare with masc. proper name Tibalt, which is from Old French Thibauld, from Germanic *Theobald (see Theobald).
Then Isegrim on the one side and Bruin on the other led the poor fox to the gallows, tibert running before with the halter.
From "tibert," "Tib," "Tibby," also was a common name for a cat.
tibert, Tybert, and Tybalt are forms of the ancient name Thibault.