In linguistics, a superfamily (or macrofamily) is a phyletic unit encompassing several language families. The term is generally used for conjectural families, e.g. the Nostratic, Dene-Caucasian, Altaic, and Proto-World groupings. The term is typically invoked to describe theoretical associations between established language families (e.g. between Turkic, Mongolian, and Tungusic languages, in the case of Altaic), and has come to carry a connotation of hypothesis, and therefore, controversy. As such, it is rarely applied to accepted groupings like the Indo-European language family.