"supporting musician," 1936, from side (adj.) + man (n.). Earlier it meant "assistant to a church warden" (1560s).
side-door
sidekick
sidelight
sideline
sidelong
sideman
sidenote
sidereal
side-saddle
sideshow
sidestep
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}