n. At certain universities, e.g. Cambridge and Dublin, a student who receives an allowance for his college expenses (study grant); originally in return for serving other (paying) students.
the GNU version of the Collaborative International Dictionary of English
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 Century Dictionary and Cyclopedia
n. At the University of Cambridge, or at Trinity College, Dublin, an undergraduate student who, in consideration of his comparative poverty, usually receives free commons. Compare servitor .
Word Usage
"He entered college as a sizar, that is, in return for doing the work of a servant he received free board and lodging in his college."