by 1840, in reference to musical instruments, past-participle adjective from mute (v.). Figuratively by 1879. Of colors by 1905. Related: mutedness.
1560s, "cause to go down," from down (adv.). Meaning "swallow hastily" is by 1860; football sense of "bring down (an opposing player) by tackling" is attested by 1887. Figurative sense of "defeat, get the better of" is by 1898. Related: Downed; downing.