- a homeless, usually mongrel, cat that scavenges for food in alleys, streets, etc.
- a homeless cat that roams in back streets
A promiscuous woman; also, a person of loose morals. For example, She’s constantly picking up men in bars—a real alley cat. This idiom transfers a stray cat that frequents alleys in search of food to a woman of easy virtue, especially a prostitute seeking customers. [Slang; early 1900s]