Added 10 October 2026 coolant /ˈkuːlənt/ noun Categories: NatureRare Words noun ! Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about coolant at Wordnik → Where our words come from → A fluid agent (gas or liquid) that produces cooling; especially one used to cool a system by transferring heat away from one part to another. he added more coolant to the car's radiator Related Words: condenserrefrigerationrefrigerantcoolercoolingfreezingchillingchillliquidfluidenginespanning Back to today's word