Grout

A mixture of cement, sand, and water used to fill the spaces between tiles.

From Old French 'grout' meaning 'coarse meal' or 'porridge,' which came from a Germanic root meaning 'to grind.' The surprise is that grout was named after breakfast food! Medieval builders noticed that the thick, pasty mixture they used to fill gaps looked exactly like the coarse porridge (grout) that common people ate. The word literally means 'construction porridge' — builders were essentially saying their mortar looked like peasant food.