Melismatic

Because slower metrical types are more melismatic and ornamented than primary-meter, their melodic-passages in both xipi and erhuang are more melismatic and complex than those of primary-meter.

Source: wiktionary

1998, Barbara Newman, Introduction, Barbara Newman (translator), Hildegard von Bingen, Symphonia: A Critical Edition of the Symphonia armonie celestium revelationum, Cornell University Press, 2nd Edition, page 28, In general, the more melismatic a piece, the more solemn, elaborate, and difficult it is, and the more the text is dominated by the music.

Source: wiktionary

The melismatic content of this chant lies at the extreme of what is typical for responsories, usually considered among the most melismatic chant types.

Source: wiktionary