A “loose cat” generally means an unowned domestic cat wandering freely outdoors, often called a stray (was once a pet, might be friendly) or feral (born wild, avoids humans). It can also refer to a cat that has escaped its home and is lost/displaced. “Loose” describes their untethered state, unlike a pet, and can also imply a lack of restraint or being in a messy condition, like having diarrhea (loose stool).