blossom out vs blossom

blossom out is not a noun while blossom is a noun.

Word	Noun	Adjective	Verb	Adverb
blossom out	No	No	Yes	No
blossom	Yes	No	Yes	No

As verbs, blossom out and blossom are synonyms defined as:

Other synonyms of blossom out include blossom forth, unfold.

blossom out (noun)	blossom (noun)
	reproductive organ of angiosperm plants especially one having showy or colorful parts
	the period of greatest prosperity or productivity

blossom out (verb)	blossom (verb)
develop or come to a promising stage	develop or come to a promising stage
	produce or yield flowers