superius
/suːˈpɪərɪəs
/noun [mass noun]
The highest voice part in early choral music; the cantus.In this final section of Kyrie I the tenor abandons formally quoting the cantus firmus and instead gives free material, bars 40-49, first heard at bars 31 in the superius.
Origin
Late 18th century: from Latin, neuter (used as a noun) of superior (see superior).