Old English scinan "shed light, be radiant, be resplendent, iluminate," of persons, "be conspicuous" (class I strong verb; past tense scan, past participle scinen), from Proto-Germanic *skinan (cf. Old Saxon and Old High German skinan, Old Norse and Old Frisian skina, Dutch schijnen, German scheinen, Gothic skeinan "to shine, appear"), from PIE root *skai- (2) "to gleam, shine, flicker" (cf. Sanskrit chaya "brilliance, luster; shadow," Greek skia "shade," Old Church Slavonic sinati "to flash up, shine," Albanian he "shadow"). Transitive meaning "to black (boots)" is from 1610s. Related: Shined (in the shoe polish sense), otherwise shone; shining.