Proto-IE: *g(')heisl- ?
Meaning: hostage, prisoner
Celtic: OIr gīall; Cymr gwystl, OCorn guistel Geisel, Bret goestl `gage, caution'; Gaul MN Congeistlus; Ir gell `Einsatz, Pfans' (< *ghislo-)
Russ. meaning: заложник, пленник
Comments: May be a borrowing from Celt to Germ.