serie would be my Swenglish for the singular of:
se·ries ( P ) Pronunciation Key (sîrz)
n. pl. series
A number of objects or events arranged or coming
one after the other in succession.
One serie in Swedish is one chain of objects/events coming one after the other in succession, series being the plural, as in more than one such thing. Perhaps that's not how English uses it, but I'll abuse the language then I guess.