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1.
A person who sucks the social life out of a social interaction.

Etymology: From physics, where a blackbody is a solid from which no radiation reflects or escapes, black holes are the most familiar example. From optics, commonly implemented as a black velvet lined box with a small window, from which no projected light escapes. Conceptually similar to heatsink (thermodynamics) and ground (electronics). Coined in early 1980s by Cindy and Jaime.

Synonym: Emotional Vampire, coined by Andrzej
Your party was happenin' until that blackbody Jonathan showed up.
by JaimeG June 22, 2007