excretion vs laxation

excretion and laxation both are nouns.

Word	Noun	Adjective	Verb	Adverb
excretion	Yes	No	No	No
laxation	Yes	No	No	No

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

Other hyponyms of excretion include defecation, shitting, incontinence, incontinency, micturition, urination.

excretion (noun)	laxation (noun)
the bodily process of discharging waste matter	the act of making something less tight
waste matter (as urine or sweat but especially feces) discharged from the body	the elimination of fecal waste through the anus