furnace: [13] Etymologically, furnace means roughly ‘warm place’. It comes via Old French fornais from Latin fornāx ‘furnace’. This was a derivative of fornus ‘oven’, a word related to formus ‘warm’, which goes back to the same Indo-European source, *ghworm-, *ghwerm-, as probably produced English warm. => fornication[furnace etymology, furnace origin, 英语词源]