c. 1400, "physical, human, mortal," from Old French carnal and directly from Latin carnalis "fleshly, of the flesh," from carnis "of the flesh," genitive of caro "flesh, meat," probably originally "a piece of flesh" (from PIE root *sker- (1) "to cut").
The meaning "sensual, pertaining to the passions and appetites of the flesh" is from early 15c.; that of "worldly, sinful, not spiritual" is from mid-15c. Carnal knowledge "sexual intercourse" is attested from early 15c. and was in legal use by 1680s. Medieval Latin carnalis meant "natural, of the same blood," a sense sometimes found in Middle English carnal.
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.