An alley cat.
alley cat definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a homeless, mongrel cat
alley cat definition by American Heritage Dictionary
nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A homeless or stray cat.
alley cat - Phrases/Idioms
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]