Source : Webster's Revised Unabridged Dictionary (1913)

Aeronautics \A`["e]r*o*naut"ics\, n.
   The science or art of ascending and sailing in the air, as by
   means of a balloon; a["e]rial navigation; ballooning.

Source : WordNet®

aeronautics
     n : the theory and practice of navigation through air or space
         [syn: {astronautics}]