French word foyer comes from Latin focus, and later Latin focarius (That which concerns the hearth A kitchen-boy.)

Detailed word origin of foyer

Dictionary entry	Language	Definition
focus	Latin (lat)	(figuratively) house, family. Firepan, coal pan, brazier. Fireplace, hearth.
focarius	Latin (lat)	That which concerns the hearth A kitchen-boy.
focārius	Late Latin (LL)
*focārium	Vulgar Latin (la-vul)
foyer	French (fra)	Hearth. Home, domicile. Household. Lobby, foyer. Source, centre, seat.

Words with the same origin as foyer