black widow

American  

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.

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black widow British  

noun

1. an American spider, Latrodectus mactans , the female of which is black with red markings, highly venomous, and commonly eats its mate

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Etymology

Origin of black widow

First recorded in 1910–15