Is a person's saying about a well-known liar, "That liar," considered backbiting, especially if said jokingly and without the intention of backbiting?

It appears the questioner has backbitten the mentioned person, because backbiting is defined as mentioning your brother with something he dislikes if it were to reach him. This mention includes whether it is in jest or otherwise, and it is not a condition to have the intention of backbiting.