(informal) The temporary inability to think properly, or to remember something

(pathology) Alternative spelling of brain fever

(pathology, dated) encephalitis or meningitis

A complex riddle or puzzle.

(slang, derogatory) A fool.

plural of der-brain

(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.

plural of brain trust