February 13, 1539

We learn some adorably obscure facts about cats in a post from Medievalists.net.

In medieval England domestic cats were known as Gyb – the short form of of Gilbert – and that name was also popular for individual pet cats. Meanwhile in France they were called Tibers or Tibert ....generic name[s for the]... domestic cat in France – Tibert the Cat was one of the characters in the Reynard the Fox animal fables.

Other names for cats included Mite, who prowled around Beaulieu Abbey in the 13th century, and Belaud, a grey cat belonging to Joachim du Bellay in the 16th century. Isabella d’Este also owned a cat named Martino. Old Irish legal texts refer to several individual cats and names them: Meone (little meow); Cruibne (little paws); Breone (little flame, perhaps an orange cat), and Glas nenta (nettle grey).
Medieval, no, obscure, no, but Isabella d'Este (May 18, 1474 to February 13, 1539) who ruled the city state of Mantua while her husband was elsewhere, was called, "The First Lady of the World," and we think, with absolutely no evidence, that her cat was one reason for the honorifics.