I would say it ¡s not any kind of noun.
Yes, the noun 'inconsistency' is an abstract noun as a word for a state of not being the same throughout; a variation; a word for a concept.
There is no abstract noun form of the adjective 'thick'.The noun form of the adjective 'thick' is thickness, a concrete noun, a word for a physical property, a physical density.The noun 'thickness' can be used in an abstract context, for example:A thickness of anticipation could be felt throughout the audience.
Yes, the noun astonishment is an abstract noun, a word for an emotional reaction.
Is undergone an abstract noun
Concrete noun
The abstract noun is criticism.
The noun 'hopefulness' is an abstract noun, a word for an emotion.
Abstract noun of hopeless
The abstract noun is obligation.
Friendship has not abstract noun because It is a abstract noun
The abstract noun form is tourism.
The abstract noun for the adjective vacant is vacantness. Another abstract noun form is vacancy.