Does "POLY-MET" unambiguously describe a capacitor type?
My first guess for what "poly-met" means was "metalized polypropylene".  However, using that abbreviation when its important this be understood clearly without additional information is irresponsible engineering.

Any competent BOM will show a part number, which is the real definition of the part.  The description is to give you a quick idea of what part to expect.  This could be a manufacturer's part number, a distributor stock number, or a in-house partnumber.  Preferably, more than one of these is filled in.  Either way, look these up to get the definitive answer.