Sour
Old English sūr, of Germanic origin; related to Dutch zuur and German sauer .
wiktionary
From Middle English sour, from Old English sūr(“sour”), from Proto-West Germanic *sūr, from Proto-Germanic *sūraz(“sour”), from Proto-Indo-European *súHros(“sour”). Cognate with West Frisian soer, Dutch zuur(“sour”), Low German suur, German sauer(“sour”), Danish, Swedish and Norwegian sur, French sur(“sour”), Faroese súrur(“sour”), Icelandic súr(“sour, bitter”).
etymonline
sour (adj.)
Old English sur "sour, tart, acid, fermented," from Proto-Germanic *sura- "sour" (source also of Old Norse surr, Middle Dutch suur, Dutch zuur, Old High German sur, German sauer), from PIE root *suro- "sour, salty, bitter" (source also of Old Church Slavonic syru, Russian syroi "moist, raw;" Lithuanian sūras "salty," sūris "cheese").
Meaning "having a peevish disposition" is from early 13c. Sense in whisky sour (1885) is "with lemon added" (1862). Sour cream is attested from 1855. French sur "sour, tart" (12c.) is a Germanic loan-word.
sour (v.)
c. 1300, from sour (adj.). Compare Old High German suren, German säuern. Related: Soured; souring.
