noun: (countable, aviation, travel) Initialism of property irregularity report: a form to be filled in when baggage is lost by an airline. [(aviation, travel) an official form to be filled out if checked baggage is lost or damaged by an airline.]
noun: (uncountable) Initialism of passive infrared.
noun: (chemistry) Abbreviation of polyisocyanurate. [(organic chemistry) A form of polyurethane polymer, based on cyanuric acid, formed from a polyhydroxy alcohol and a diisocyanate; it forms foams that are used for thermal insulation]
