cartoon mouse character created 1928 by U.S. animator Walt Disney (1901-1966). As an adjective meaning "small and worthless, petty, inconsequential" it was in use by 1951, perhaps from the popularity of the cheaply made Mickey Mouse wristwatch; it was used by 1935 in reference to mediocre dance-band music, based on the type of tunes played as background in cartoon films.
Michelson-Morley
Michigan
mick
mickey
Mickey Finn
Mickey Mouse
mickle
Micmac
micro-
microbe
microbial