inhabitants of the torrid zone, who "haue the Sunne twice euery yeere in their zenith, and then they make no shaddowes at all" [Nathanael Carpenter, "Geographie Delineated forth in Two Bookes," 1635], from Medieval Latin Ascii, from Greek askioi, from a- "not, without," privative prefix (see a- (3)), + skia "shade, shadow" (see shine (v.)).

Online Etymology Dictionary, © 2010 Douglas Harper