In grammar the superlative of an adjective or adverb is the greatest form of adjective or adverb which indicates that something has some feature to a greater degree than anything it is being compared to in a given context. For example, if Adam is 45, Bess is 35, and Chris is 25, Adam is the oldest of the three, because his age transcends those of Bess and Chris in one direction, while Chris is the youngest, because his age transcends those of Adam and Bess in the other direction. If Dan, who is 50, and Edna, who is 20, join the group, Dan now becomes the oldest and Edna the youngest.
Some prescriptive grammars hold that, when comparing only two entities, use of the superlative is ungrammatical: if the group were to contain only Adam and Bess, Adam would be older, while Bess would be younger and it would be ungrammatical to say that Adam was the oldest. The superlative degree used in reference to sets of two or fewer are found, however, in writing and speech. In an offer for auction to the "highest bidder" in which only one bid were received, for example, no rule of English grammar would negate the sale.
Many ancient grammarians object to the use of the superlative or comparative with words such as "full," "complete," "unique" or "empty," which by definition already denote either a totality, an absence, or an absolute. However, such words are routinely and frequently qualified in contemporary speech and writing. This type of usage conveys more of a figurative than a literal meaning. For example, in the phrase "most complete selection of wines in the Midwest," "most complete" doesn't mean "closest to having all elements represented," it merely connotes a well-rounded, relatively extensive selection. Browsing in some of the best-known search-engines for "more complete" or "most complete" would establish the frequency of this usage by many millions of examples.
In English, the superlative and the comparative are created by inflecting adjectives or adverbs. The structure of a superlative consists normally of the positive stem of the adjective or adverb, plus the suffix -est, or (especially in words of a Latin or Romance origin) the modifier "most" or "least" before the adjective or adverb. It always has the definite article and is completed by "of" or other preposition plus one or more nouns of entities that it surpasses to the highest or greatest degree, such as in "he is the tallest of/in the class," or "the town is the most beautiful in the country."
Mention should be made also of the elative, which is not an actual separate inflection but the intensified degree of adverbs and adjectives. Adjectives at the elative do not refer to other objects, like a superlative does; e.g., "she is very beautiful"; "she is most beautiful" (intensification in this case means "very beautiful indeed"). Simply put; the word 'superlative' is defined as:
In contrast to English, in the grammars of most romance languages the elative and the superlative are joined into the same degree (superlative), which can be of two kinds: comparative (e.g. "the most beautiful") and absolute (e.g. "very beautiful").
French: The superlative is created from the comparative by inserting the definitive article (la, le, or les) before "plus" or "moins" and the adjective determining the noun. For instance: Elle est la plus belle femme → (she is the most beautiful woman); Cette ville est la moins chère de France → (this town is the least expensive in France).
Spanish: The comparative superlative, like in French, has the definite article (such as "las", "el"), or the possessive article (such as "tus", "nuestra", "su"), followed by the comparative ("más" or "menos"), so that "el meñique es el dedo más pequeño" is "the pinky is the smallest finger." Irregular comparatives are "mejor" for "bueno" and "peor" for "malo" which can be used as comparative superlatives also by adding the definite article or possessive article, so that, "nuestro peor error fue casarnos" is "our worst mistake was to get married."
The absolute superlative is normally formed by modifying the adjective by adding -ísimo, -ísima, -ísimos or -ísimas, depending on the gender or number. So that "¡Los chihuahuas son perros pequeñísimos!" is "Chihuahuas are such tiny dogs!" Some irregular superlatives are "máximo" for "grande", "pésimo" for "malo", "ínfimo" for "bajo", "óptimo" for "bueno", "acérrimo" for "acre", "paupérrimo" for "pobre", "celebérrimo" for "célebre".
Note the difference between comparative superlative and absolute superlative: Ella es la más bella → (she is the most beautiful); Ella es bellísima → (she is extremely beautiful).
For the comparative superlative they use the words "mais" and "più" between the article and the adjective, like "most" in English.
For the absolute superlative they either use "muito"/"molto" and the adjective or modify the adjective by taking away the final vowel and adding issimo (singular masculine), issima (singular feminine), íssimos/issimi (plural masculine), or íssimas/issime (plural feminine). For example:
There are some irregular forms for some words ending in "-re" and "-le" derivating from Latin words ending in "-er", and "-ilis" that have a superlative form similar to the Latin one. In the first case words lose the ending "-re" and they gain the endings errimo (singular masculine), errima (singular feminine), érrimos/errimi (plural masculine), or érrimas/errime (plural feminine); in the second case words lose the "-l"/"-le" ending and gain ílimo/illimo (singular masculine), ílima/illima (singular feminine), ílimos/illimi (plural masculine), or ílimas/illime (plural feminine), the irregular form for words ending in "-l"/"-le" is somehow rare and, in Italian but nor is Portuguese, it exists only in the archaic or literary language. For example:
Scottish Gaelic: When comparing one entity to another in present or future tense, the adjective is changed by adding an e to the end and i before the final consonant(s) if the final vowel is broad. Then, the adjective is preceded by nas to say "more," and as to say "most." (The word na is used to mean than.) Adjectives that begin with f are lenited. Nas and as use different syntax constructions. For example:
As in English, some forms are irregular, i.e. nas fheàrr (better), nas miosa (worse), etc.
In other tenses, nas is replaced by na bu and as by a bu, both of which lenite the adjective if possible. If the adjective begins with a vowel or an f followed by a vowel, the word bu is reduced to b'. For example:
Welsh is similar to English in many respects. The ending -af is added onto regular adjectives in a similar manner to the English -est, and with (most) long words -mwyaf precedes it, as in the English most. Also, many of the commonest adjectives are irregular. Unlike English, however, when comparing just two things, the superlative must be used, e.g. of two people - John ydy'r talaf (John is the tallest).