circularize vs diffuse

circularize is not an adjective while diffuse is an adjective.

Word	Noun	Adjective	Verb	Adverb
circularize	No	No	Yes	No
diffuse	No	Yes	Yes	No

As verbs, circularize and diffuse are synonyms defined as:

circularize (adjective)	diffuse (adjective)
	(of light) transmitted from a broad light source or reflected
	spread out; not concentrated in one place
	lacking conciseness

circularize (verb)	diffuse (verb)
make circular	cause to become widely known
cause to become widely known	spread or diffuse through
distribute circulars to	move outward
canvass by distributing letters
canvass by using a questionnaire