coo ‧ lant /ˈkuːlənt/ BrE AmE noun [uncountable and countable] technical
[ Word Family: noun : ↑ cool , ↑ coolness , ↑ cooler , ↑ coolant ; verb : ↑ cool ; adverb : ↑ coolly ; adjective : ↑ cool ]
a liquid or gas used to cool something, especially an engine