1580s, "action of distorting; state of being twisted out of shape," from Latin distortionem (nominative distortio), noun of action from past-participle stem of distorquere "to twist different ways, distort," from dis- "completely" (see dis-) + torquere "to twist" (from PIE root *terkw- "to twist").
Figurative use (of words, etc.), "a perversion of the true meaning or intent" is from 1640s. Meaning "change in the wave-form of a signal by an electronic device" is from 1887, specifically of amplifiers by 1962.
