Superlative grades of adjectives express the maximum level of a quality. They either compare an individual subject to the group or category he belongs to (relative superlative), or they express a high quality level without making a comparison (absolute superlative).
Relative superlative corresponds to the English forms the (adjective)...est (i.e. the highest, the fattest, the darkest, etc.), and the most... (adjective) (the most interesting, the most exciting, etc.).
To obtain this in Italian, the adverb più is used; it is the same adverb used for comparative of majority (see paragraph 12.1), but by adding a definite article in front of più the maximum grade is expressed.
più nuovo di ... = newer than ... il più nuovo (di ...) = the newest (of ...)
Also the opposite, i.e. the minority relative superlative, can be regularly formed, by replacing il più with il meno (the least), whereas in English this pattern is not used as much as in Italian.
il meno giovane (di...) = the least young (of...) In this case, probably the eldest would be preferred to the least young.
Both the adjective and the article have to match the subject's number (i.e. singular or plural), according to the general rules.
However, the article's and adjective's gender points to the group or category the subject belongs to (which is not always the same gender of the subject itself). The following sample sentences analyze in detail the choice of the article.
The subject is Marco (singular, masculine); the group or category the subject belongs to is amici (plural, masculin).
Therefore, the article and adjective required are singular (as Marco) and masculine (as amici).
Among singular masculine articles, il, lo, l' (see paragraph 2.4), in this case the first of the three will be chosen because it matches phonetically the following word (più).
la balena è il più lungo dei mammiferi = the whale is the longest among mammals
Here the subject of the sentence is balena (singular, feminine), the category is mammiferi (masculine, plural).
The article and the adjective required are singular (as balena) and masculine (as mammiferi, despite the subject is feminine).
Try yourself this analysis with the following examples:
il cane è il più fedele degli animali = the dog is the most faithful among animals
il Monte Everest è la più alta delle montagne = Mount Everest is the highest among (all) mountains era il più anziano dei miei insegnanti = he was the oldest among my teachers
la matematica è la più interessante delle materie scolastiche = maths is the most interesting among school subjects
By turning the sentence the other way round this match is easier to understand:
il più lungo dei mammiferi è la balena = the longest among mammals is the whale
In the aforesaid sentence, the article il and the adjective lungo are masculine, because evidently referred to mammiferi (masculine), but they are singular as the noun balena.
Here are further examples:
la pizza è il più famoso dei piatti italiani = pizza is the most famous among Italian dishes (pizza feminine singular - piatti masculine plural)
Turning the sentence the other way round, we have:
il più famoso dei piatti italiani è la pizza = the most famous among Italian dishes is pizza (pizza feminine singular - piatti masculine plural)
More examples:
il coraggio è la più importante delle virtù = courage is the most important among virtues
(coraggio masculine singular - virtù feminine plural: being a truncated word, singular and plural are identical)
i batteri sono le più minute delle specie viventi = bacteria are the tiniest among living species (batteri masculine plural - specie feminine plural)
Note that the preposition di does not express a real comparison, as it does with comparative, but only the subject's belonging to a category or group (i.e. di = of), although in English di would be often translated as among.
As an alternative to preposition di, the group or category may be also introduced by the prepositions tra or fra, both meaning among. They are easier to use for who is not yet familiar with compound prepositions (see paragraph 5.2), since fra and tra never bind to the following article: they always remain simple prepositions followed by the article.
il whisky è la più forte delle bevande alcoliche = whisky is the strongest among alcoholic drinks il whisky è la più forte fra le bevande alcoliche = whisky is the strongest among alcoholic drinks Carlo era il più alto dei nostri amici = Charles was the tallest among our friends
Carlo era il più alto fra i nostri amici = Charles was the tallest among our friends Roma era la più grande delle città antiche = Rome was the largest among ancient cities Roma era la più grande fra le città antiche = Rome was the largest among ancient cities When using il meno (minority relative superlative), fra or tra are preferrred to di:
il topo è il meno grande dei mammiferi = the mouse is the least large (= the smallest) among mammals il topo è il meno grande fra i mammiferi (preferrable) = the mouse is the least large (i.e. the smallest) among mammals
la Moldavia è la meno ricca delle nazioni europee = Moldavia is the least rich among the European countries
la Moldavia è la meno ricca fra le nazioni europee (preferrable) = Moldavia is the least rich among the European countries
Sentences that contain a relative superlative may be turned the other way round, i.e. opening the sentence with among.... In this case, the use of fra (or tra) is preferred to di; alternatively, tutti or tutte (all) is added after fra (tra) or di.
il whisky è la più famosa tra le bevande alcoliche = whisky is the most famous among alcoholic drinks
fra le bevande alcoliche la più famosa è il whisky = among alcoholik drinks, the most famous one is whisky
fra le bevande alcoliche il whisky è la più famosa = among alcoholik drinks, whisky is the most famous one
fra tutte le bevande alcoliche il whisky è la più famosa = among all alcoholik drinks, whisky is the most famous one
fra tutte le bevande alcoliche la più famosa è il whisky = among all alcoholik drinks, whisky is the most famous one
di tutte le bevande alcoliche il whisky è la più famosa = (same as above)
di tutte le bevande alcoliche la più famosa è il whisky = (same as above)
Roma era la più potente delle città antiche = Rome was the most powerful among the ancient cities
fra le città antiche Roma era la più potente = among the ancient cities, Rome was the most powerful one
fra le città antiche la più potente era Roma = among the ancient cities, the most powerful one was Rome
fra tutte le città antiche Roma era la più potente = among all the ancient cities, Rome was the most powerful one
fra tutte le città antiche la più potente era Roma = among all the ancient cities, the most powerful one was Rome
di tutte le città antiche Roma era la più potente = (same as above)
di tutte le città antiche la più potente era Roma = (same as above)
The part of the sentence shifted to the bottom is the one that receives more emphasis.
In English too the sentence can be turned the other way round, but one has to be added, whereas in Italian no addition is required.
When the sentence starts with among..., in Italian the definite article may be replaced with the relevant demonstrative pronoun:
fra le bevande alcoliche il whisky è la più famosa = among alcoholik drinks, whisky is the most famous one
fra le bevande alcoliche il whisky è quella più famosa = (same as above)
fra tutti i nostri amici Carlo è il più alto = among all our friends, Charles is the tallest