E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A tom-cat. The male cat used to be called Gilbert. Nares says that Tibert or Tybalt is the French form of Gilbert, and hence Chaucer in his Romance of the Rose, renders Thibert le Cas by Gibbe, our Cat (v. 6204). Generally used for a castrated cat. (See TYBALT.)
I am as melancholy as a gib cat or a lugged bear.Shakespeare: 1 Henry IV., i. 2.