watchfulness vs watchful

watchfulness is a noun but watchful is not a noun.

Word	Noun	Adjective	Verb	Adverb
watchfulness	Yes	No	No	No
watchful	No	Yes	No	No

watchfulness (noun)	watchful (noun)
vigilant attentiveness
the process of paying close and continuous attention

watchfulness (adjective)	watchful (adjective)
	engaged in or accustomed to close observation
	experiencing or accompanied by sleeplessness
	carefully observant or attentive; on the lookout for possible danger