Why turkey has the same name as Turkey
brain damage n.
Injury to the brain that is caused by various conditions, such as head trauma, inadequate oxygen supply, infection, or intracranial hemorrhage, and that may be associated with a behavioral or functional abnormality.
1. [generalisation of "Honeywell Brain Damage" (HBD), a theoretical disease invented to explain certain utter cretinisms in Honeywell Multics] Obviously wrong; cretinous; demented. There is an implication that the person responsible must have suffered brain damage, because he should have known better. Calling something brain-damaged is really bad; it also implies it is unusable, and that its failure to work is due to poor design rather than some accident. "Only six monocase characters per file name? Now *that's* brain-damaged!"
2. [especially in the Mac world] May refer to free demonstration software that has been deliberately crippled in some way so as not to compete with the commercial product it is intended to sell. Synonym crippleware.