casemate

Etymology

From French casemate, from Italian casamatta. Further origin unclear, could be a compound casa (“house”) + matta (“mat (of straw), roof made of such material”), or borrowed from Greek χάσματα (chásmata) the plural of χάσμα (chásma, “gap”), presumably referring to the loopholes for shooting from.

noun

1. (military) A bombproof chamber, usually of masonry, in which cannon may be placed, to be fired through embrasures; or one capable of being used as a magazine, or for quartering troops.
2. (architecture) A hollow molding, chiefly in cornices.