width vs wideness

width and wideness both are nouns.

Word	Noun	Adjective	Verb	Adverb
width	Yes	No	No	No
wideness	Yes	No	No	No

As nouns, wideness is a hyponym of width; that is, wideness is a word with a more specific, narrower meaning than width:

Other hyponyms of width include broadness, beam, narrowness.

width (noun)	wideness (noun)
the extent of something from side to side	the property of being wide; having great width
	unusual largeness in size or extent or number