refrigerant

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Cooling or freezing; refrigerating.
• adjective Medicine Reducing fever.
• noun A substance, such as air, ammonia, water, or carbon dioxide, used to provide cooling either as the working substance of a refrigerator or by direct absorption of heat.
• noun Medicine An agent used to reduce fever.

from The Century Dictionary.

• Abating heat; cooling.
• noun Anything which abates the sensation of heat, or cools.
• noun Figuratively, anything which allays or extinguishes.
• noun A refrigerating agent; a refrigerator.

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

• noun That which makes to be cool or cold; specifically, a medicine or an application for allaying fever, or the symptoms of fever; -- used also figuratively.
• adjective Cooling; allaying heat or fever.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective That cools or freezes
• noun A substance used in a heat cycle that undergoes a phase change between gas and liquid to allow the cooling, as in refrigerators, air conditioners, etc.
• noun That which makes cool or cold, such as a medicine for allaying the symptoms of fever.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective causing cooling or freezing
• noun any substance used to provide cooling (as in a refrigerator)