superlative

US /səˈpɝː.lə.t̬ɪv/
UK /səˈpɝː.lə.t̬ɪv/
"superlative" picture
1.

of the highest quality or degree

:
The chef prepared a superlative meal for the guests.
Her performance was truly superlative.
1.

the highest degree of comparison of an adjective or adverb (e.g., 'biggest', 'most beautiful')

:
In grammar, 'tallest' is the superlative form of 'tall'.
She used the superlative 'most beautiful' to describe the sunset.