nu·ée ar·dente 
(n-ā ăr-däɴt)
(n-ā ăr-däɴt)n. pl. nuées ardentes (n-āz ăr-däɴt)
A fast-moving cloudlike mass consisting of gases, hot ash, and other material ejected from an erupting volcano.
[French : nuée, large cloud, thundercloud (from nue, cloud, high clouds; see NUANCE) + ardente, feminine of ardent, burning (from Old French ardant; see ardent in the Appendix of Indo-European roots).]
nuée ardenteeruption of Mt. St. Helens,
Skamania County, Washington
August 7, 1980