Source : Webster's Revised Unabridged Dictionary (1913)

Aviation \A`vi*a"tion\, n.
   The art or science of flying.

Source : WordNet®

aviation
     n 1: the aggregation of a country's military aircraft [syn: {air
          power}]
     2: the operation of aircraft to provide transportation
     3: the art of operating aircraft [syn: {airmanship}]
     4: travel via aircraft; "air travel involves too much waiting
        in airports"; "if you've time to spare go by air" [syn: {air
        travel}, {air}]