fixedness vs fixed

fixedness is a noun but fixed is not a noun.

Word	Noun	Adjective	Verb	Adverb
fixedness	Yes	No	No	No
fixed	No	Yes	No	No

fixedness (noun)	fixed (noun)
the quality of being fixed in place as by some firm attachment
the quality of being fixed and unchangeable
remaining in place

fixedness (adjective)	fixed (adjective)
	securely placed or fastened or set
	(of a number) having a fixed and unchanging value
	fixed and unmoving
	incapable of being changed or moved or undone; e.g. "frozen prices"