Source : Webster's Revised Unabridged Dictionary (1913)

Suffocative \Suf"fo*ca*tive\, a.
   Tending or able to choke or stifle. ``Suffocative catarrhs.''
   --Arbuthnot.

Source : WordNet®

suffocative
     adj : causing difficulty in breathing especially through lack of
           fresh air and presence of heat; "the choking June
           dust"; "the smothering soft voices"; "smothering heat";
           "the room was suffocating--hot and airless" [syn: {smothering},
            {suffocating}]