Source : Webster's Revised Unabridged Dictionary (1913)

Sapsago \Sap"sa*go\, n. [G. schabzieger; schaben to shave, to
   scrape + zieger a sort of whey.]
   A kind of Swiss cheese, of a greenish color, flavored with
   melilot.

Source : WordNet®

sapsago
     n : a hard green Swiss cheese made with skim-milk curd and
         flavored with clover