The Collaborative International Dictionary of English v.0.48:

Schoolfellow \School"fel`low\, n.
   One bred at the same school; an associate in school.
   [1913 Webster]

WordNet (r) 3.0 (2006):

schoolfellow
    n 1: an acquaintance that you go to school with [syn:
         schoolmate, classmate, schoolfellow, class fellow]