premise: <mask>, once.  Seconda volta, second time, points to certain modifications in the close of a repeated strain.
hypothesis: the best context for <mask> here is A turning; a time; -- chiefly used in phrases signifying that the part is to be repeated one, two, or more times; but not A timekeeper; especially, a watch by which small intervals of time can be measured; a kind of stop watch. It is used for timing the speed of horses, machinery, etc..