1.NounA convex volcanic structure made of generally viscous, felsic lava, which grows slowly over time by extrusion from a volcanic edifice, either endogenously, by inflating from within, or exogenously, as erupted flow lobes of lava.
"Lava domes are rarely seen in shield volcanos.; Mount St. Helens has been building a new lava dome since the May, 1980 eruption."