Mouser/ˈmaʊsər/ Definition 1 of 2Pro Tip 1/3Associative Imagery Imagine a cat in a farm setting as mousers are historically linked to pest control there. The farmer praised his tabby as a champion mouser. Pro Tip 2/3Not Just Cats Remember, while cats are typical mousers, some dogs and other animals can also be mousers. Our Jack Russell terrier is a surprisingly good mouser. Pro Tip 3/3Common Usage 'Mouser' often comes up in rural or household contexts when discussing animals that hunt mice. We need a good mouser to control the mice in the shed.