Origin and history of thanage

Middle English thein, from Old English þegn "military follower, one who holds lands in exchange for military service," also "vassal, retainer, attendant," from Proto-Germanic *thegnas (source also of Old Saxon thegan "(free) follower, warrior; boy, youngling," Old Norse þegn "thane, freeman," Old High German thegan, German Degen "thane, warrior, hero").

This is reconstructed to be from PIE *tek-no- (source also of Sanskrit takman "descendant, child," Greek teknon "child; young animal, shoot"), from root *tek- "to beget, give birth to" (source also of Greek tekos "child, the young of animals," tokos "childbirth, offspring, produce of money, interest"). However, Beekes writes that the identification of the Greek and Germanic words is "not without problems" caused by phonetics.

Also used in Old English for "disciple of Christ." The specific sense of "man who ranks between an earl and a freeman" is late 15c.

The modern spelling is from Scottish, where early 13c. it came to mean "chief of a clan, king's baron," and it has predominated in English probably due to the influence of "Macbeth;" normal orthographic changes from Old English ðegn would have produced Modern English *thain. Some historians now use thegn to distinguish Anglo-Saxon thanes from Scottish thanes.

word-forming element in nouns of act, process, function, condition, from Old French and French -age, from Late Latin -aticum "belonging to, related to," originally neuter adjectival suffix, from PIE *-at- (source of Latin -atus, past participle suffix of verbs of the first conjugation) + *-(i)ko-, secondary suffix forming adjectives (see -ic).