In 1721, a member of the Royal Society of London, Thomas Forster of Boston, wrote The World alarm’d. A surprizing relation of a New Burning Island lately raised out of the Sea near Tercera; with a brief history of the other ignivomous mountains at this day in the world. By ignivomous, he meant that the mountain was vomiting fire.
He might instead have called it a volcano, since that word had been in the language for a century by then — a work of 1669 by the German Jesuit Athansius Kircher was entitled The Vulcano’s or Burning and Fire-vomiting Mountains (the apostrophe in “volcano’s” would give modern copy editors a momentary spasm, but it was common then, because the word seemed foreign and odd).
Ignivomous has a splendid ring to it, even better than in its exact French equivalent ignivome. That was a favourite word of Jules Verne’s and ignivomous appears in several of his translated works, including The Field of Ice, in which it describes the volcano that the intrepid explorers of the story found, in defiance of known geography, at the North Pole: “This enormous ignivomous rock in the middle of the sea was six thousand feet high, just about the altitude of Hecla.”
The word comes from Latin ignis, meaning fire, plus vomere, to vomit. Note that it’s pronounced with the stress on the second syllable.