quench vs cool down

quench and cool down both are verbs.

Word	Noun	Adjective	Verb	Adverb
quench	No	No	Yes	No
cool down	No	No	Yes	No

As verbs, cool down is a hypernym of quench; that is, cool down is a word with a broader meaning than quench:

Other hypernyms of quench include chill, cool.

quench (verb)	cool down (verb)
suppress or crush completely	make cool or cooler
cool (hot metal) by plunging into cold water or other liquid	loose heat
reduce the degree of (luminescence or phosphorescence) in (excited molecules or a material) by adding a suitable substance	lose intensity
satisfy (thirst)
suppress (sparking) when the current is cut off in an inductive circuit, or suppress (an oscillation or discharge) in a component or device
put out, as of fires, flames, or lights