early 15c., "to misuse, misapply" (power, money, etc.), from Old French abuser "deceive, abuse, misuse" (14c.), from Vulgar Latin *abusare, from Latin abusus "an abusing; a using up," past participle of abuti "use up, consume," also "to misuse, abuse, misapply, outrage," from ab "off, away from" (see ab-) + uti "use" (see use).
Also in reference to forbidden sexual situations from early 15c., but originally meaning incest, masturbation (self-abuse), homosexuality, prostitution, etc. From 1550s specifically as "to misuse sexually, ravish," but OED 2nd ed. marks this obsolete and the modern use "subject (someone) to unwanted sexual activity" is likely a fresh coinage from late 20c. Specifically of drugs, from 1968. Meaning "attack with harsh language, revile" is from c. 1600. Related: Abused; abusing.
Old English self, sylf (West Saxon), seolf (Anglian), "one's own person, -self; own, personal; same, identical," from Proto-Germanic *selbaz (source also of Old Norse sjalfr, Old Frisian self, Dutch zelf, Old High German selb, German selb, selbst, Gothic silba), Proto-Germanic *selbaz "self," from PIE *sel-bho-, suffixed form of root *s(w)e-, pronoun of the third person and reflexive (referring back to the subject of a sentence), also used in forms denoting the speaker's social group, "(we our-)selves" (see idiom).
Its use as the second element in compounded reflexive pronouns (herself, etc.) was in Old English, from the original independent (and inflected) use of self following personal pronouns, as in ic selfa "myself," min selfes "of myself." With a merging of accusative, dative, and genitive cases.
As a noun from c. 1200 as "the person or thing previously specified;" early 14c. as "a person in relation to that same person." G.M. Hopkins used selve as a verb, "become or cause to become a unique self" (1880) but its use seems to have been restricted to poets.