Question: what are armchair covers called?
Answer: An antimacassar /ˌæntɪməˈkæsər/ is a small cloth placed over the backs or arms of chairs, or the head or cushions of a sofa, to prevent soiling of the permanent fabric underneath. The name also refers to the cloth flap 'collar' on a sailor's shirt or top, used to keep macassar oil off the uniform.