thermophore

from The Century Dictionary.

• noun A device to prevent undue cooling of the masks used in the administration of ether. For this purpose ample provision is made for the conduction of heat, through a metallic attachment, to the surfaces cooled by evaporation.

from the GNU version of the Collaborative International Dictionary of English.

• noun An apparatus for conveying heat, as a case containing material which retains its heat for a considerable period.