in·ha·lant 
(ĭn-hālənt)
(ĭn-hālənt)adj.
Used in or for inhaling.
n.
1. A drug, such as an anesthetic or bronchodilator, or another substance, such as saline solution, inhaled for medicinal purposes in vapor or aerosol form.
2. A substance inhaled as an intoxicant, usually in the form of a vapor.