Melisma/Melismatic

A question has come up about the meaning of "melismatic." You may not know what the word means, but you certainly know what it is!

A melisma is a series of notes set to one syllable. A great example is my joke about the "born melisma." (You know, the joke about that Matt Damon movies. (Well, I guess it's even less funny now that I'm putting it into print...))

In the chorus "Unto Us a Child is Born," there are many running notes on the word "born." That's a melisma.

In Gregorian chant, there are two main types of chant: syllabic and melismatic. (There's also neumatic chant, and that's somewhere between syllabic and melismatic.)

A syllabic chant has--you guessed it--one syllable per note:


A melismatic chant is very florid with multiple notes per syllable:


Which movements of Messiah are the most melismatic?