Singing more than one note on a single syllable. To be used in moderation. Abused to the point of absurdity by R'n'B and pop singers (usually but not always female) as a way of showing off vocal capabilities, much like an Yngwie Malmsteen solo. Egregious offenders include Mariah Carey, Celine Dion, Christina Aguilera, and Boyz II Men.
Sometimes called runs, or vocal runs.
Quit with the melisma, bitch! "Yeah" does not have 23 syllables!