Origin and history of lief

"permission, liberty granted to do something," Old English leafe "leave, permission, licence," dative and accusative of leaf "permission," from Proto-Germanic *laubo (source also of Old Norse leyfi "permission," and, with prefix, Old Saxon orlof, Old Frisian orlof, German Urlaub "leave of absence"), from PIE root *leubh- "to care, desire, love," the original idea being "approval resulting from pleasure." It is a noun relative of lief "dear" (adj.); and compare belief. In the military sense, it is attested from 1771.

"sweetheart, paramour, loved one" (archaic), c. 1200, lemman, "loved one of the opposite sex; paramour, lover; wife;" also "a spiritually beloved one; redeemed soul, believer in Christ; female saint devoted to chastity; God, Christ, the Virgin Mary;" also a term of intimate address to a friend or lover, contracted from late Old English leofman, a compound of leof "dear" (see lief) + man "human being, person" (from PIE root *man- (1) "man").

Originally of either gender, though in deliberate archaic usage it tends to be limited to women. Often in religious use in early Middle English, of brides of Christ, the spiritually beloved of God, etc.; by c. 1300 it could mean "betrothed lover," and by late 14c. it had the pejorative sense "concubine, mistress, gallant." For loss of medial -f-, compare had.