Source : Webster's Revised Unabridged Dictionary (1913)

Alumnus \A*lum"nus\, n.; pl. {Alumni}. [L., fr. alere to
   nourish.]
   A pupil; especially, a graduate of a college or other
   seminary of learning.

Source : WordNet®

alumnus
     n : a person who has received a degree from a school (high
         school or college or university) [syn: {alumna}, {alum},
         {graduate}, {grad}]
     [also: {alumni} (pl)]