I came across this when reading the Taktika of Leo VI. The skoulkatores were a group of soldiers assigned in the Byzantine army to scout or spy on the enemy, usually under the cover of darkness or by hiding under foliage.
I felt that this was too much of a coincidence to pass up, since "skulking" means to to sneak around, but especially "in the shadows". The words are too similar to be false cognates. I looked up a few dictionaries and found that most of them attribute the etymology of the word to 12th Century Scandinavia, and I was thinking...hmm... did the Varangians bring it back with them?
Nonetheless, it seems to me that the dictionaries are wrong. I'm not sure if skoulka derives from Greek or Latin, but I've never heard it used before. Would anyone care to comment on this theory?
I'm pretty sure the dictionaries are correct, and this is a coincidence. The Norwegian word 'skulk' means 'truancy/vagrancy', and it's from this that the English word - meaning to loiter in an area with dubious intent - comes. It's highly unlikely that the Norwegian word derives from Byzantine Greek, not just because there's no real commonality of meaning between 'battle scout' and 'vagrant', but also because the Norwegian word predates the Varangians.
Do you have any evidence that the dictionaries are wrong? Because languages are full of coincidences like this.
This question would likely get a much better(and faster) answer from /r/asklinguistics.
I'll tell you what the OED has to say about it:
Etymology: apparently of Scandinavian origin: compare Norwegian skulka to lurk, lie >watching, Danish skulke, Swedish skolka to shirk, play truant.
There is apparently a remarkable lack of evidence for the currency of the word in the 15th >and 16th centuries, compared with its frequency in earlier and later use.
The OED approximates the first known use of the word (then spelt scullion) to about 1200-1230.
/r/etymology exists