DAU /dow/ [German Fidonet] n. German acronym for D"ummster Anzunehmender User (stupidest imaginable user). From the engineering-slang GAU for Gr"osster Anzunehmender Unfall, worst foreseeable accident, esp. of a LNG tank farm plant or something with similarly disastrous consequences. In popular German, GAU is used only to refer to worst-case nuclear acidents such as a core meltdown. See cretin, fool, loser and weasel.