alastrim n a mild form of smallpox caused by a less virulent form of the virus Usage(s) They had no idea what traveler had carried the disease or where he had come from, but the smallpox proved to be the mild form, variola minor or alastrim. Synonym(s) variola minor pseudosmallpox pseudovariola milk pox white pox West Indian smallpox Cuban itch Kaffir pox