In vocal music, contrafactum (pl. contrafacta) refers to "the substitution of one text for another without substantial change to the music".[1]
While translations meant for singing do not usually constitute intentional "substitution", examples of contrafacta which do constitute wholesale substitution of a different text include the following types:
While the above examples involve either music that is in the public domain or lyrics that were modified by the original lyricist, one obvious consideration in producing a contrafactum of someone else's music in modern times is the copyright of the original music or lyrics upon which the contrafactum would be based.