convertible vs inconvertible

convertible is a noun but inconvertible is not a noun.

Word	Noun	Adjective	Verb	Adverb
convertible	Yes	Yes	No	No
inconvertible	No	Yes	No	No

convertible (noun)	inconvertible (noun)
a car that has top that can be folded or removed
a sofa that can be converted into a bed
a corporate security (usually bonds or preferred stock) that can be exchanged for another form of security (usually common stock)

convertible (adjective)	inconvertible (adjective)
capable of being exchanged for or replaced by something of equal value	used especially of currencies; incapable of being exchanged for or replaced by another currency of equal value
designed to be changed from one use or form to another	not capable of being changed into something else
capable of being changed in substance as if by alchemy