英语词源字典 - 在线词源网站

besides (prep.)[besides 词源字典]: attested from c. 1200 (common after c. 1400), from beside + adverbial genitive -s. Once sharing all the senses of beside, now properly limited to "in addition to, otherwise."[besides etymology, besides origin, 英语词源]
burnsides (n.): style of facial hair consisting of side whiskers and a mustache (but clean-shaven chin), 1875 (singular; plural form from 1878; many early uses are in college and university magazines), a reference to U.S. Army Gen. Ambrose E. Burnside (1824-1881) of Civil War fame, who wore them and inspired the style. Compare sideburns.
sideshow (n.): also side-show, 1855, "minor exhibition alongside or near a principal one," apparently a coinage of P.T. Barnum's, from side (adj.) + show (n.). Hence, any diversion or distracting event.
sidestep (n.): also side-step, 1757, "a stepping to the side" (originally in military drill), from side (adj.) + step (n.). The verb is recorded from 1895; the figurative sense is attested from 1900.