sickness vs prostration

sickness and prostration both are nouns.

Word	Noun	Adjective	Verb	Adverb
sickness	Yes	No	No	No
prostration	Yes	No	No	No

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

sickness: impairment of normal physiological function affecting part or all of an organism
prostration: an abrupt failure of function or complete physical exhaustion

sickness (noun)	prostration (noun)
impairment of normal physiological function affecting part or all of an organism	the act of assuming a prostrate position
the state that precedes vomiting	abject submission; the emotional equivalent of prostrating your body
defectiveness or unsoundness	an abrupt failure of function or complete physical exhaustion