Of the highest order, quality, or degree; surpassing or superior to all others. Excessive or exaggerated. Grammar Of, relating to, or being the extreme degree of comparison of an adjective or adverb, as in best or brightest. Something of the highest possible excellence. The highest degree; the acme. Grammar The superlative degree. Grammar An adjective or adverb expressing the superlative degree, as in brightest, the superlative of the adjective bright, or most brightly, the superlative of the adverb brightly.