Definition of black pill:
(n) :
(often attributive) A notional pill taken by those who have adopted a nihilistic, usually (but not necessarily) far-right philosophy, especially incels who believe unattractive men will never be sexually or romantically successful, or those who are pessimistic about social or political issues.
(n) :
(philosophy) A hypothetical pill with a specific probability of causing death, which one is offered a large sum of money in order to take, as a philosophical dilemma.
(n) :
(slang) An opium pill.
(n) :
A poison pill; a pill intended to kill the person who ingests it.
(n) :
A traditional Tibetan remedy.
(n) :
Used other than figuratively or idiomatically: see black, pill.