volcano UK /vɒlˈkeɪ.nəʊ/US /vɑlˈkeɪ.noʊ/noun 2verb 1forms 4 noun2 •a hill or mountain formed where hot rock and gas come up through a hole in the earthIceland's volcanoes are among the most active on Earth. •A kind of firework producing an upward plume of sparks. verb1 •to erupt; to burst forthShe shrank back, the words volcanoed, words that stabbed again, and yet again — 1951 formsvolcanoed · volcanoing · volcanoes · volcanos