whiteout vs white out

whiteout is a noun but white out is not a noun.

Word	Noun	Adjective	Verb	Adverb
whiteout	Yes	No	Yes	No
white out	No	No	Yes	No

As verbs, whiteout and white out are synonyms defined as:

whiteout (noun)	white out (noun)
an arctic atmospheric condition with clouds over snow produce a uniform whiteness and objects are difficult to see; occurs when the light reflected off the snow equals the light coming through the clouds

whiteout (verb)	white out (verb)
lose daylight visibility in heavy fog, snow, or rain	widen the interlinear spacing by inserting leads
cover up with a liquid correction fluid	cover up with a liquid correction fluid