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.”
Britain's peerage system, which dates to Anglo-Saxon times, consists of five ranks: duke, marquess, earl, viscount and baron, according to Debrett's, a leading source of information on the British peerage system.
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.
The meaning of EARL is a member of the British peerage ranking below a marquess and above a viscount.
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, n. meanings, etymology, pronunciation and more in the Oxford English Dictionary
The Earl, also known as the Count, is the third most powerful among the nobility ranks. The rank of the Earl was lower than that of the Duke or the Marquess, but he could exert power over the Viscounts and Barons.