unalarming vs alarm

unalarming is not a noun while alarm is a noun.

Word	Noun	Adjective	Verb	Adverb
unalarming	No	Yes	No	No
alarm	Yes	No	Yes	No

unalarming (noun)	alarm (noun)
	a device that signals the occurrence of some undesirable event
	a clock that wakes a sleeper at some preset time
	an automatic signal (usually a sound) warning of danger
	fear resulting from the awareness of danger

unalarming (adjective)	alarm (adjective)
not alarming; assuaging alarm

unalarming (verb)	alarm (verb)
	warn or arouse to a sense of danger or call to a state of preparedness
	fill with apprehension or alarm; cause to be unpleasantly surprised