The Collaborative International Dictionary of English v.0.48:

Salutatorian \Sa*lu`ta*to"ri*an\, n.
   The student who pronounces the salutatory oration at the
   annual Commencement or like exercises of a college, -- an
   honor commonly assigned to that member of the graduating
   class who ranks second in scholarship. [U.S.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

salutatorian
    n 1: a graduating student with the second highest academic rank;
         may deliver the opening address at graduation exercises
         [syn: salutatorian, salutatory speaker]