auto-alarm vs autoalarm

auto-alarm and autoalarm both are nouns.

Word	Noun	Adjective	Verb	Adverb
auto-alarm	Yes	No	No	No
autoalarm	Yes	No	No	No

As nouns, auto-alarm and autoalarm are synonyms defined as:

auto-alarm and autoalarm: a radio receiving device used on ships that rings an alarm bell when a distress signal is received.

auto-alarm (noun)	autoalarm (noun)
a radio receiving device used on ships that rings an alarm bell when a distress signal is received.	a radio receiving device used on ships that rings an alarm bell when a distress signal is received.