(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.

(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.

plural of brain trust

The migration of educated or talented people from less economically advanced areas to more economically advanced areas, especially to large cities or richer countries.

(medicine) An irreversible loss of brain function and cessation of brain activity.

Alternative spelling of brain-dead

(medicine, not comparable) Having an irreversible loss of brain function and cessation of brain activity. / (colloquial) Having no useful thoughts; stupid; ditzy.

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

(pathology, dated) encephalitis or meningitis