noun. ['ˌpɑːˌliːˈproʊpəˌliːn'] a polymer of propylene used as a thermoplastic molding material.
1. Noun, singular or mass Melt a polypropylene welding rod into the ditch in the front of the bumper with a hot air gun. 2. Adjective Loosen each screw that holds a hinge in position against the panel if polypropylene shims are behind the hinge. 3. Verb, past participle Bend a paperclip, and slide it between the hinge and wood panel if the door has polypropylene shims.