Something placed in, against, or near the mouth. A covering for the mouth, esp. for protection or restraint; a face mask; a gumshield.

In extended use. Any of a number of things (as a mask, a veil, etc.) which may be placed over the face, esp. for protection; (in later use) spec.…

A mask, helmet, etc., providing a means of filtering or otherwise modifying inhaled air, esp. one worn to prevent the inhalation of dust, smoke…

A contrivance for inhaling. An appliance enabling a person to breathe with safety in a deleterious atmosphere or under water; a respirator.

(see quots.).

Any of several forms of respirator, esp. one with a portable supply of air for use by divers and miners. Now historical.

Of, relating to, or containing an open circuit; spec. designating a breathing apparatus in which air is exhaled into the atmosphere and so lost to…

An apparatus for drawing in or inhaling air or vapour. A kind of respirator: see quot. 1898.

The portion of an inhaler or respirator which covers the face.

(a) a helmet used by firemen, enabling the wearer to see and breathe freely in the midst of smoke; also, a similar helmet used by others; (b) a…

= gas mask, n. 2.

A mask worn to provide protection against poisonous gas.

= gas mask, n.

a mask fitting over the nose and mouth through which oxygen or oxygen-enriched air is supplied.

= inhaler, n. 2.

a complete, unbroken circuit; frequently attributive; spec. (a) a complete electrical circuit formed entirely of conductive material; (b) a…