Melisma (Greek: μέλισμα, melisma, song, air, melody; from μέλος, melos, song, melody, plural: melismata) is the singing of a single syllable of text while moving between several different notes in succession. Music sung in this style is referred to as melismatic, as opposed to syllabic, in which each syllable of text is matched to a single note

https://en.wikipedia.org/wiki/Melisma