Comparison is a feature in the morphology or syntax of some languages whereby adjectives and adverbs are rendered in an inflected or periphrastic way to indicate a comparative degree, property, quality, or quantity of a corresponding word, phrase, or clause. A superlative construction expresses the greatest quality, quantity, or degree relative to all other comparators.

The associated grammatical category is degree of comparison. The usual degrees of comparison are the positive, which simply denotes a property (as with the English words big and fully); the comparative, which indicates greater degree (as bigger and more fully); and the superlative, which indicates greatest degree (as biggest and most fully). Some languages have forms indicating a very large degree of a particular quality (called elative in Semitic linguistics). Other languages (e.g. English) can express lesser degree, e.g. beautiful, less beautiful, least beautiful.

The comparative degrees are frequently associated with adjectives and adverbs because these words take the -er suffix or modifying word more or less. (e.g., faster, more intelligent, less wasteful). Comparison can also, however, appear when no adjective or adverb is present, for instance with nouns (e.g., more men than women). However, the usage of the word than between nouns simply denotes a comparison made and not degree of comparison comparing the intensity or the extent of the subjects. One preposition, near, also has comparative and superlative forms, as in Find the restaurant nearest your house.