-issimo

(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.)

-issimo

1. Added to an adjective, creates an adjective. This suffix is an intensifier which adds a qualifier of "extremely" or "remarkably."[1]

• IPA^(key): /ˈis.si.mo/
• Rhymes: -issimo
• Hyphenation: -ìs‧si‧mo

Borrowed from Latin -issimus. Compare Spanish -ísimo and Portuguese -íssimo which are partly based on the Italian forms.

-issimo (adjective-forming suffix, feminine -issima, masculine plural -issimi, feminine plural -issime)

1. added to adjectives to form superlatives

   ‎buono (“good”) + ‎-issimo → ‎buonissimo (“as good as it gets, extremely good”)

   ‎grave (“serious”) + ‎-issimo → ‎gravissimo (“very serious”)

   ‎consigliato (“recommended”) + ‎-issimo → ‎consigliatissimo (“highly recommended”)

   ‎sconsigliato (“not recommended, inadvisable”) + ‎-issimo → ‎sconsigliatissimo (“lowly recommended, highly inadvisable”)

   ‎primo (“first”) + ‎-issimo → ‎primissimo (“very first”)

-issimo (adverb-forming suffix)

1. added to adverbs to form superlatives

   ‎bene (“well”) + ‎-issimo → ‎benissimo (“very well”)

   ‎spesso (“often”) + ‎-issimo → ‎spessissimo (“very often”)

   ‎piano (“softly”) + ‎-issimo → ‎pianissimo (“very softly”)

   ‎lentamente (“slowly”) + ‎-issimo → ‎lentissimamente (“very slowly”)

   ‎velocemente (“fastly”) + ‎-issimo → ‎velocissimamente (“very fastly”)

-issimo m (noun-forming suffix, plural -issimi)

1. (often humorous) added to some nouns to form extremes

   ‎poltrona (“seat”) + ‎-issima → ‎poltronissima (“front row seat”)

   ‎finale (“final”) + ‎-issima → ‎finalissima (“grand final”)

• -issima (after feminine nouns)

• Terms formed with this suffix are invariably stressed on the antepenult.
• The adjectival and adverbial suffix can be used multiple times for emphasis, when the suffix is used multiple times it drops its last vowel except the last time:

  bellissimo ― very beautiful

  bellissimissimo ― very very beautiful

  ...

• When the adverbial suffix is used together with the suffix -mente, the suffix -issimo becomes -issima and it is always before the suffix -mente:

  velocissimamente ― very fast

  velocissimissimamente ― very very fast

  ...

• The stress of -issimo is always stronger than the stress of -mente.

-issimo (non-lemma form of verb-forming suffix)

1. added to the stem of verbs ending in -ire to form the first-person plural imperfect subjunctive tense

   ‎salire + ‎-issimo → ‎salissimo (“that we be raised, gone up, etc; that we have risen, gone up”)

• (Classical) IPA^(key): /ˈis.si.moː/, [ˈɪs̠ːɪmoː]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈis.si.mo/, [ˈisːimo]

-issimō

1. superlative degree of -ō