heat ray vs irradiation

heat ray and irradiation both are nouns.

Word	Noun	Adjective	Verb	Adverb
heat ray	Yes	No	No	No
irradiation	Yes	No	No	No

As nouns, irradiation is a hypernym of heat ray; that is, irradiation is a word with a broader meaning than heat ray:

Other hypernyms of heat ray include beam, beam of light, light beam, ray, ray of light, shaft, shaft of light.

heat ray (noun)	irradiation (noun)
a ray that produces a thermal effect	(medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance
	the apparent enlargement of a bright object when viewed against a dark background
	(Pavolvian conditioning) the elicitation of a conditioned response by stimulation similar but not identical to the original stimulus
	(physiology) the spread of sensory neural impulses in the cortex
	a column of light (as from a beacon)
	the condition of being exposed to radiation