Sentence:  Through 1911 and 1912 , as the Cubist facet-plane 's tendency to adhere to the literal <WSD>surface</WSD> became harder and harder to deny , the task of keeping the surface at arm's length fell all the more to eye-undeceiving contrivances . 
Meaning of the word marked with <WSD> tags:  the extended two-dimensional outer boundary of a three-dimensional object