Source : Webster's Revised Unabridged Dictionary (1913)

Inhale \In*hale"\, v. t. [imp. & p. p. {Inhaled}; p. pr. & vb.
   n. {Inhaling}.] [L. inhalare to breathe upon; pref. in- in +
   halare to breathe: cf. F. inhaler. Cf. {Exhale}.]
   To breathe or draw into the lungs; to inspire; as, to inhale
   air; -- opposed to {exhale}.

         Martin was walking forth to inhale the fresh breeze of
         the evening.                             --Arbuthnot.

Source : WordNet®

inhaling
     adj : breathing in