Grimalkins is an old-fashioned word for a type of cat. It is also known as a mouser or a tomcat. Other synonyms for grimalkins include feline, kitty, tabby, moggy, and pussy. These words are often used interchangeably, but they each have slightly different connotations. For example, feline is a more scientific term for a cat, while moggy is a colloquial term used in the UK. Regardless of which word is used, it is clear that cats are beloved pets and important members of many households, regardless of what they are called.