illusion vs irradiation

illusion and irradiation both are nouns.

Word	Noun	Adjective	Verb	Adverb
illusion	Yes	No	No	No
irradiation	Yes	No	No	No

As nouns, irradiation is a hyponym of illusion; that is, irradiation is a word with a more specific, narrower meaning than illusion:

illusion: an erroneous mental representation
irradiation: the apparent enlargement of a bright object when viewed against a dark background

Other hyponyms of illusion include apparition, fantasm, phantasm, phantasma, phantom, shadow, phantom limb.

illusion (noun)	irradiation (noun)
the act of deluding; deception by creating illusory ideas	(medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance
an illusory feat; considered magical by naive observers	the apparent enlargement of a bright object when viewed against a dark background
something many people believe that is false	(Pavolvian conditioning) the elicitation of a conditioned response by stimulation similar but not identical to the original stimulus
an erroneous mental representation	(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