9 letters · 17 points in Scrabble
verb make resistant to fire
adjective impervious to damage by fire
originEtymology tree Proto-Indo-European *péh₂wr̥ Proto-Germanic *fōr Proto-West Germanic *fuir Old English fȳr Middle English fyr English fire English -proof English fireproof From fire + -proof.
Etymology from Wiktionary, CC BY-SA 3.0