“Ettercap” means two things at once: a spider, and a bad-tempered or spiteful person. It comes from Old English attorcoppa — ator (poison, venom) plus coppa (spider) — and that second element is still hiding in plain sight inside cobweb, literally a spider’s web. Tolkien revived the older form in The Hobbit, where Bilbo taunts the Mirkwood spiders with it; as Anu Garg notes, no spider has ever liked being called attercop.