P0180800 (pûr)n.1. The soft vibrant sound made by a cat.2. A sound similar to that made by a cat: the purr of an engine.v.purred, purr·ing, purrsv.intr. To make or utter a soft vibrant sound: The cat purred. The sewing machine purred.v.tr. To express by a soft vibrant sound.[Imitative.]