The noun form for the adjective authentic is authenticity.
No, nationally is the adverb form. The adjective is national.
The noun form of the adjective 'dangerous' is dangerousness.The word 'dangerous' is the adjective form of the noun danger.The noun form of the adjective 'childish' is childishness.The word 'childish' is the adjective form of the noun child.The noun form of the adjective 'beautiful' is beautifulness.The word 'beautiful' is the adjective form of the noun beauty.
The adjective meaning of or about a nation is national.There is also an adjective for nationalism, which is nationalistic.
The noun form of the adjective 'wide' is wideness.A related noun form is width.
The noun form of the adjective 'comfortable' is comfortableness.The word 'comfortable' is the adjective form of the noun comfort.
The abstract noun form of the adjective unique is uniqueness.
The abstract noun form for the adjective convenient is convenience.
The noun form for the adjective hilarious is hilariousness. A related noun form is hilarity.
The noun form of the adjective 'modest' is modestness.A related noun form is modesty.
The noun form of the adjective close is closeness.
The word 'weakest' is the superlative form of the adjective 'weak':positive: weakcomparative: weakersuperlative: weakest