Source : Webster's Revised Unabridged Dictionary (1913)

Oxonian \Ox*o"ni*an\, a.
   Of or relating to the city or the university of Oxford,
   England. --Macaulay.

Oxonian \Ox*o"ni*an\, n.
   A student or graduate of Oxford University, in England.

Source : WordNet®

Oxonian
     adj 1: of or pertaining to or characteristic of Oxford University;
            "Oxonian education"
     2: of or pertaining to or characteristic of the city of Oxford,
        England, or its inhabitants; "his Oxonian neighbors";
        "Oxonian bookstores"
     n : a resident of Oxford