an American spider, Latrodectus mactans, the female of which is black with red markings, highly venomous, and commonly eats its mate
2.
a female suicide bomber, esp a Chechen rebel
black widow in American English
US
an American spider (Latrodectus mactans), the female of which has a glossy black body with an hourglass-shaped red mark underneath, and a poisonous bite which is normally not fatal
so called because the female sometimes eats its mate