tolerating no opposition or resistance; irresistible
Word origin
[1595–1605; oppose + -less]This word is first recorded in the period 1595–1605. Other words that entered Englishat around the same time include: premium, redundant, toss, vernacular, zero-less an adjective suffix meaning “without” (childless; peerless), and in adjectives derived from verbs, indicating failure or inability to performor be performed (resistless; tireless)