The headword is a late Greek variant of the word more commonly spelled ski/pwn (sigma 618).
[1] = Synagoge sigma111, Photius sigma311 Theodoridis (with the spelling ski/pwn); similarly in Hesychius and elsewhere, including a scholion on Aristophanes, Wasps 727 (on which see below). On skapa/nion, a dialectal variant of the more common skhpa/nion, see sigma 575.
[2] An approximation of what the chorus-leader says in Aristophanes, Wasps 725-7, exhibiting the accusative plural form of the headword with the spelling ski/pwnas. MacDowell 233 comments that this phrase must be a regular idiom for surrendering, like the English 'throw in the sponge/towel'; it is, however, otherwise unattested.