Pet form of Katherine, also frequently used as an independent given name, which has been extremely popular since the 1980s. It is often found in combination with other names such as Ann, Jane, Leigh, Louise, and Mae.
English and Scottish: patronymic from the personal name John. As an American family name, Johnson has absorbed patronymics and many other derivatives of this name in continental European languages. (For forms, see Hanks and Hodges 1988.)