Spider is the original sense, from Old English attor, poison + cop, which usually meant head/summit but possibly also just spider itself, as it is also the root behind the first half of cobweb. The dialect sense is from Yorkshire and points north, with the idea of spiders and crabby people are both venomous. Its best known use in standard English is in one of Bilbo's songs from The Hobbit, when he's taunting the giant spiders of Mirkwood:
Old fat spider spinning in a tree!---L.
Old fat spider can’t see me!
Attercop! Attercop!
Won’t you stop,
Stop your spinning and look for me!
