1530s, of armies, "to retreat, draw back," also, of persons, "to withdraw" to some place, especially for the sake of privacy; from French retirer "to withdraw (something)," from re- "back" (see re-) + Old French tirer "to draw" (see tirade). Related: Retired; retiring.
The sense of "leave one's business or occupation" is by 1660s. The meaning "to leave company and go to bed" is from 1660s. Transitive sense is from 1540s, originally "withdraw, lead back" (troops, etc.); meaning "to remove from active service" is from 1680s. Baseball sense of "to put out" (a batter or team) is recorded by 1874.
word-forming element in legal English (and in imitation of it), representing the Anglo-French -é ending of past participles used as nouns (compare -y (3)). As these sometimes were coupled with agent nouns in -or, the two suffixes came to be used as a pair to denote the initiator and the recipient of an action.
Not to be confused with the French -ée that is a feminine noun ending (as in fiancée), which is from Latin -ata.
<a href="https://www.etymonline.com/word/retiree">Etymology of retiree by etymonline</a>
Harper, D. (n.d.). Etymology of retiree. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/retiree