Source : Webster's Revised Unabridged Dictionary (1913)

Sizar \Si"zar\, n.
   One of a body of students in the universities of Cambridge
   (Eng.) and Dublin, who, having passed a certain examination,
   are exempted from paying college fees and charges. A sizar
   corresponded to a servitor at Oxford.

         The sizar paid nothing for food and tuition, and very
         little for lodging.                      --Macaulay.

   Note: They formerly waited on the table at meals; but this is
         done away with. They were probably so called from being
         thus employed in distributing the size, or provisions.
         See 4th {Size}, 2.