Attercop is actually a word in English too, although really really antiquated. The only time I've seen it used is when Bilbo was taunting the spiders of Mirkwood in The Hobbit.

The OED (not that OED) says that the English etymology is from Old English "attorcoppe", with "ator" meaning poison or venom, and "copp" meaning head, round, summit.

Cop also has some relation to the word spider in general, like in "cobweb".