COUSIN, a term of relationship (Late Lat. cosinus, perhaps an abbreviation of the classic Latin consobrinus). Children of brothers and sisters are to each other first cousins, or cousins german; the children of first cousins are to each other second cousins; the child of a first cousin is to the first cousin of his father or mother a first cousin once removed.
The word cousin has also, since the 16th century, been used by sovereigns as an honorific style in addressing persons of exalted, but not equal, sovereign rank, the term "brother" being reserved as the style used by one sovereign in addressing another.