1520s, from Latin extenuatus, past participle of extenuare "lessen, make small, reduce, diminish, detract from," from ex- "out" (see ex-) + tenuare "make thin," from tenuis "thin" (see tenet). Used over the years in a variety of literal and figurative senses in English. Related: Extenuated; extenuating. Extenuating circumstances (1660s) are those which lessen the magnitude of guilt (opposed to aggravating).