Originally a pet form of Robert, from the short form Rob + the diminutive suffix -in (of Old French origin), but now nearly always used as an independent name. In recent years it has been increasingly used as a girl's name, partly under the influence of the vocabulary word denoting the bird.
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.)