Word Study
gasmask
CIDE DICTIONARY
gasmask, n.
a mask with a filter which protects the face and lungs against poisonous gases. It is used in warfare, and also by police to allow them to effectively use tear gas or other disabling gas to disperse a crowd or force fugitives to leave a building. [WordNet 1.5]
For further exploring for "gasmask" in Webster Dictionary Online