Jarl n. : A chief; an earl; in English history, one of the leaders in the Danish and Norse invasions.

Example:
What is the difference between the words 'chieftain' and 'Jarl'?

Taxonomy
earls, jarl, shire, king, coronet, rank, power, Scandinavia, English, Iceland, earls of Oxford, surname, England, earls of Essex, Scotland, the earls, free encyclopedia, List of earldoms.

Defination from the web:
jarl the Scandinavian form of a title meaning "chieftain" and referring especially to chieftains set to rule a territory in a king's stead. ... Only one person ever held the title of Earl (or Jarl) in Iceland. ...