Old English salo "dusky, dark" (related to sol "dark, dirty"), from Proto-Germanic *salwa- (source also of Middle Dutch salu "discolored, dirty," Old High German salo "dirty gray," Old Norse sölr "dirty yellow"), from PIE root *sal- (2) "dirty, gray" (source also of Old Church Slavonic slavojocije "grayish-blue color," Russian solovoj "cream-colored"). Related: Sallowness.