prion Definition

any of several small petrels (genus Pachyptila of the family Procellariidae) of the southern hemisphere that are bluish gray above and white below

prion protein; especially : an abnormal form of prion protein that in mammals includes pathogenic forms which arise sporadically, as a result of genetic mutation, or by transmission (as by ingestion of infected tissue) and which upon accumulation in the brain cause a prion disease (such as bovine spongiform encephalopathy or Creutzfeldt-Jakob disease)

any of a group of spongiform encephalopathies that are caused by prions and that include bovine spongiform encephalopathy, Creutzfeldt-Jakob disease, kuru, scrapie, and variant Creutzfeldt-Jakob disease —called also transmissible spongiform encephalopathy

a glycoprotein found especially on the cell surface of neurons in the brain and spinal cord that sometimes occurs in an abnormal misfolded form which proliferates by inducing the normal protein to convert to the misfolded pathogenic form —abbreviation PrP