Source : Webster's Revised Unabridged Dictionary (1913)

Cupful \Cup"ful\ (k?p"f?l), n.; pl. {Cupfuls} (-f?lz).
   As much as a cup will hold.

Source : WordNet®

cupful
     n : the quantity a cup will hold; "he drank a cup of coffee";
         "he borrowed a cup of sugar" [syn: {cup}]