black widow

noun
1.
a venomous spider, Latrodectus mactans, widely distributed in the U.S., the female of which is jet-black with an hourglass-shaped red mark on the underside of its abdomen.
Origin
1910-15
British Dictionary definitions for black widow

black widow

noun
1.
an American spider, Latrodectus mactans, the female of which is black with red markings, highly venomous, and commonly eats its mate
Word Origin and History for black widow
n.

type of poisonous spider (Latrodectus mactans) in U.S. South, 1904, so called from its color and from the female's supposed habit of eating the male after mating (they are cannibalistic, but this particular behavior is rare in the wild). Sometimes also known as shoe-button spider. The name black widow is attested earlier (1830s) as a translation of a name of the "scorpion spider" of Central Asia.