air lock vs airlock

air lock and airlock both are nouns.

Word	Noun	Adjective	Verb	Adverb
air lock	Yes	No	No	No
airlock	Yes	No	No	No

As nouns, air lock and airlock are synonyms defined as:

air lock and airlock: a chamber that provides access to space where air is under pressure

air lock (noun)	airlock (noun)
a chamber that provides access to space where air is under pressure	a chamber that provides access to space where air is under pressure