From Longman Dictionary of Contemporary Englishldoce_024_ibig catˌbig ˈcat noun [countable] 
HBAa large animal of the cat family, such as a lion or tiger
HBAa large animal of the cat family, such as a lion or tigerExamples from the Corpus
big cat• A poster for the local paper on the wall next to the newsagent claims boldly that another big cat has been seen.• As it came near he quickly lowered the camera and directed a wide-eyed stare, straight at the big cat.• So I ask him if he saw the big cat.• In fact he reminded me of a cat, a very big cat, slow and smooth and self-contained. 