- side (n.)
- Old English side "flanks of a person, the long part or aspect of anything," from Proto-Germanic *sithon (cf. Old Saxon sida, Old Norse siða, Middle Dutch side, Old High German sita, German Seite), from adjective *sithas "long" (cf. Old English sid "long, broad, spacious," Old Norse siðr "long, hanging down"), from PIE root *se- "long, late" (see soiree). Original sense preserved in countryside.
Figurative sense of "position or attitude of a person or set of persons in relation to another" (cf. choosing sides) first recorded mid-13c. Meaning "music on one side of a phonograph record" is first attested 1936. Phrase side by side "close together and abreast" is recorded from c.1200. Restaurant phrase on the side "apart from the main dish" is attested from 1884, American English. Side-splitting "funny" is first attested 1860.
- side (v.)
- "to cut into sides" (of meat), late 15c., from side (n.). Meaning "to support one of the parties in a discussion, dispute, etc.," is first attested 1590s, from side (n.) in the figurative sense; earlier to hold sides (late 15c.). Related: Sided; siding.