The Polish word "PR INST MET NIEZELAZ" refers to non-iron metal fittings, and although it may not have a direct synonym in English, there are several phrases and terms that can be used to convey a similar meaning. Some synonyms include "non-ferrous metal fittings", "non-iron alloy components" or "metal fixtures free of iron content". These terms describe fittings or fixtures made from metals other than iron, like aluminum, copper, or brass. Using these alternatives can help clarify the type of material being referred to and enhance communication within the context of metalworks and construction projects.