The Collaborative International Dictionary of English v.0.48:

Inhaler \In*hal"er\, n.
   1. One who inhales.
      [1913 Webster]

   2. An apparatus for inhaling any vapor or volatile substance,
      such as ether or chloroform, or an aerosol mist of a
      solution, for medicinal purposes; as, he alway carried his
      inhaler around in his pocket in case he had asthmatic
      attack.
      [1913 Webster +PJC]

   3. A contrivance to filter, as air, in order to protect the
      lungs from inhaling damp or cold air, noxious gases, dust,
      etc.; also, the respiratory apparatus for divers.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Inhalant \In*hal"ant\, n.
   An apparatus also called an inhaler (which see); also, that
   which is to be inhaled, especially a medicine taken by
   inhalation.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

inhaler
    n 1: a dispenser that produces a chemical vapor to be inhaled in
         order to relieve nasal congestion [syn: inhaler,
         inhalator]