Sentence:  He told Sancho to pick up the helmet, and he taking it in his hands said: / "By God the basin is a good one, and worth a real of eight if it is worth a maravedis," and handed it to his master, who immediately put it on his head, turning it round, now this way, now that, in search of <WSD>fitment</WSD>, and not finding it he said, "Clearly the pagan to whose measure this famous head-piece was first forged must have had a very large head; but the worst of it is half of it is wanting." 
Meaning of the word marked with <WSD> tags:  The proper positioning and orientation of a thing for it to serve its designed purpose.