(neuroanatomy, anatomy) The part of the brain that connects the spinal cord to the forebrain and cerebrum.

(physics) A hypothetical self-aware entity that arises due to random fluctuations of spacetime.

(informal) A pain in the head from eating or drinking something cold; a cold-stimulus headache / (psychology) Failure to remember something, with the sense that recall is imminent.

(idiomatic) One's own idea or conception.

(slang) To shoot in the head.

plural of brain trust

plural of brains trust

plural of brain fart

plural of brain-washing

Suffering from an injury to the brain.