suspiciousness vs suspicion

suspiciousness and suspicion both are nouns.

Word	Noun	Adjective	Verb	Adverb
suspiciousness	Yes	No	No	No
suspicion	Yes	No	No	No

As nouns, suspiciousness and suspicion are synonyms defined as:

suspiciousness (noun)	suspicion (noun)
being of a suspicious nature	being of a suspicious nature
	doubt about someone's honesty
	an impression that something might be the case
	the state of being suspected