Portuguese

Suffix

-íssimo m ‎(feminine -íssima, plural -íssimos, feminine plural -íssimas)

1. forms the absolute superlative

   caro ‎(“expensive”) + ‎-íssimo → ‎caríssimo ‎(“extremely expensive”)

   feio ‎(“ugly”) + ‎-íssimo → ‎feiíssimo ‎(“extremely ugly”)

Usage notes

• Though both are called superlatives, Portuguese words suffixed with -íssimo are not equivalent to English words suffixed with -est or preceded by most. Instead, they are equivalent to using the adverbs very or extremely to qualify the adjective.
• Adjectives ending in -ável or -ível are suffixed with -abilíssimo or -ibilíssimo instead, replacing the suffix:

  aceitável ‎(“acceptable”) + ‎-íssimo → ‎aceitabilíssimo

• Adjectives ending in m change it to n:

  comum ‎(“common”) + ‎-íssimo → ‎comuníssimo

• Adjectives ending in -ão change it to -an:

  são ‎(“sane”) + ‎-íssimo → ‎saníssimo

• Adjectives ending in z change it to c:

  feliz ‎(“happy”) + ‎-íssimo → ‎felicíssimo.

• Adjectives ending in the semivowel followed by a vowel lose the semivowel, in nonstandard usage:

  feio ‎(“ugly”) + ‎-íssimo → ‎feíssimo (nonstandard)

  feio ‎(“ugly”) + ‎-íssimo → ‎feiíssimo (standard)

• Some words may loan the superlative from Latin in addition to forming one with this suffix:

  paupérrimo (loaned from pauperrimus) and pobríssimo, superlatives of pobre

• Colloquially, the syllable <ssi> may be repeated a number of times for emphasis:

  grande ‎(“big”) + ‎-issíssimo → ‎grandissíssimo ‎(“very very big”)