An earl has the title Earl of [X] when the title originates from a placename, or Earl [X] when the title comes from a surname. In either case, he is referred to as Lord [X], and his wife as Lady [X].
This Celtic title was rendered jarl by the Norsemen, and under Alexander I (d. 1124) it began to be replaced by earl (comes) as a result of Anglo-Norman influence. In Ireland the duke of Leinster is, as earl of Kildare, premier earl as well as premier duke. An earl is addressed as “Right Honourable” and is styled “My Lord.”
Historically, an earl was the ruler of a county or earldom, but the title is now primarily ceremonial. In the U.K., there are currently around 190 earls. The Earl of Wessex is the highest-ranking earl in the peerage system. He’s also second in line to the British throne.
Known as the peerage system, this noble hierarchy consists of five ranks today: duke, marquess, earl, viscount, and baron. The title of earl — the oldest in the peerage system — dates back to the end of the early medieval period, during the reign of King Canute (or Cnut) in the 11th century.
EARL definition: a British nobleman of a rank below that of marquis and above that of viscount: called count for a time after the Norman conquest. The wife of an earl is a countess. See examples of earl used in a sentence.
Instead of pressing home their attack, the Lancastrian troops set about plundering the town until the earl persuaded some of his men to go back to the battlefield.