Proto-IE: *kʷsep-
Meaning: darkness, dark
Hittite: ispant- c. 'Nacht' (Tischler 409ff)
Old Indian: kṣáp- (gen. kṣapáḥ), kṣapā́ f. `night'
Avestan: xšap- 'Dunkelheit'
Old Greek: pséphas, pséphos n. `Dunkel, Finsternis', psepharó- `dunkel, finster, wolkig'
Russ. meaning: темнота, темный