latrotoxin UK /ˈlæt.ɹəˌtɒk.sɪn/US /ˌlæt.ɹəˈtɑk.sɪn/ noun1 •Any of a group of neurotoxins found in the venom of spiders of the genus Latrodectus.The black widow spider injects a neurotoxin called α-latrotoxin in its venom, which causes the release of acetylcholine and catecholamines at the neuromuscular junction. — 2007 formslatrotoxins