Earldom n. : The jurisdiction of an earl; the territorial possessions of an earl.

Earldom n. : The status, title, or dignity of an earl.

Example:
What is the difference between an Earldom and a duchy?

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

Defination from the web:
Earldom) Jump to: navigation, search ... Some shires were grouped together into larger units known as earldoms, headed by an ealdorman or earl. Under Edward the Confessor earldoms like Wessex, Mercia, East Anglia and Northumbria—names that represented earlier ...