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.
That which makes cool or cold, such as a medicine for allaying the symptoms of fever.
1783, Hugh Blair, Lectures on Rhetoric and Belles Lettres, Dublin: Whitestone et al., Volume 2, Lecture 32, p. 403,
[…] never give warning that you are about to be pathetic; and call upon your hearers, as is sometimes done, to follow you in the attempt. This almost never fails to prove a refrigerant to passion.
adjective
(obsolete) That cools or freezes; providing relief from heat or fever.
1627, Francis Bacon, Sylua Syluarum: or A Naturall Historie in Ten Centuries, London: William Lee, VIII. Century, p. 204,
This Experiment may be transferred vnto the Cure of Gangrenes, either Comming of themselues, or induced by too much Applying of Opiates: Wherein you must beware of Dry Heat, and resort to Things that are Refrigerant, with an Inward Warmth, and Vertue of Cherishing.
1859, Richard Francis Burton, The Lake Regions of Central Equatorial Africa, Journal of the Royal Geographical Society of London, Volume 29, Chapter 2, pp. 54-55,
They employ the coco-nut extensively; […] This immoderate use of the fruit is, according to the people, far from wholesome: it is considered, by its refrigerant properties, to cause rheumatic pains […]