-issimo

To form the absolute superlative, follow these steps:

1. Find the Stem: Remove the final vowel from the adjective (e.g., stanc-o, grand-e).
2. Add the Suffix: Attach -issimo, -issima, -issimi, or -issime based on the noun's gender and number. Note that adjectives ending in -e (like intelligente) must now agree in gender (e.g., intelligentissimo or intelligentissima).

Adverbs with -issimo:
The suffix -issimo can also be attached to common adverbs to intensify their meaning. Unlike adjectives, adverbs are invariable, so the suffix always ends in -o. Common examples include bene → benissimo (very well), molto → moltissimo (very much), tardi → tardissimo (very late), and spesso → spessissimo (very often).

Alternative Forms:
The most common way to express this in everyday speech is by placing an adverb like molto or tanto before the adjective (e.g., molto stanco). Another very common method in everyday spoken Italian is simply repeating the adjective (e.g., un caffè caldo caldo, sono stanco stanco). The adverb assai is also used, though it is more common in Southern Italy or in formal writing. You can also use prefixes like stra- (e.g., straricco), super- (e.g., superbello), iper- (e.g., ipersensibile), and arci- (e.g., arcistufa) for informal intensification in modern spoken Italian.

Spelling Rules:

• Adjectives in -co/-go: The superlative stem generally matches the plural stem. If the plural takes an 'h' to keep the hard sound, so does the superlative (e.g., stanco → stanchissimo, ricco → ricchissimo, largo → larghissimo). If the plural takes a soft sound, the superlative does too (e.g., simpatico → simpaticissimo, amico → amicissimo, nemico → nemicissimo).
• Adjectives in -io: If the 'i' is unstressed, drop it (e.g., saggio → saggissimo, vecchio → vecchissimo). If the 'i' is stressed, keep both (e.g., pio → piissimo). A notable exception is ampio, which traditionally becomes amplissimo (though ampissimo is also accepted).

Irregular Forms:
Some adjectives have special forms derived from Latin. While ottimo and pessimo are very common, others are more specific:

• buono → ottimo (excellent)
• cattivo → pessimo (terrible)
• grande → grandissimo (very big) or massimo (maximum/limit)
• piccolo → piccolissimo (very small) or minimo (minimum/limit)
• alto → altissimo (very high) or supremo / sommo (supreme/highest)
• basso → bassissimo (very low) or infimo (lowest/inferior)

Note that while grandissimo and piccolissimo are standard choices for physical size, massimo and minimo are extremely common in everyday, informal Italian (e.g., Questo è il massimo!, Non ho la minima idea), as well as to indicate specific limits.

Non-Gradable Adjectives:
Prescriptively, adjectives that already express an absolute or extreme quality (e.g., enorme, infinito, morto) cannot take the -issimo suffix. However, Italian speakers frequently break this rule in colloquial speech for strong expressive emphasis (e.g., mortissimo for 'dead tired').

In formal or literary contexts, adjectives ending in -ebre, -acre, and -ero take the suffix -errimo (e.g., celebre → celeberrimo, misero → miserrimo, integro → integerrimo). You may also encounter -entissimo (e.g., benevolentissimo). While most of these are rare, acerrimo (from acre) is extremely common in everyday Italian (e.g., acerrimo nemico, 'bitter enemy').