Formation of Italian Plural Nouns Ending in -O

Formazione del Plurale: Nomi in -O

Making nouns ending in O plural
Camilla Bandeira

Italian singular nouns that end in -o form the plural by changing the ending to -i:

  • bambino—bambini
  • impiegato—impiegati
  • sasso—sassi
  • coltello—coltelli

The plural of the noun uomo is also formed with -i, but with a change in the ending: uomini. Of the few female nouns that end in -o, some remain unchanged in the plural; mano usually becomes mani; eco, which in the singular is feminine, is always masculine in the plural: gli echi.

  • Nouns in -co and -go do not follow a consistent behavior in forming the plural. If there is a pattern to speak of, the nouns maintain the velar consonants /k/ and /g/, and end in -chi and -ghi. However, if the nouns are sdruccioli (stressed on the third-to-last syllable of a word), instead, drop the velar consonants /k/ and /g/ and add the palatal sounds -ci and -gi:
  • baco—bachi
  • cuoco—cuochi
  • fungo—funghi
  • albergo—alberghi
  • medico—medici
  • sindaco—sindaci
  • teologo—teologi
  • ornitologo—ornitologi

Among nouns that behave differently from the conventional pattern are:

  • nemico—nemici
  • amico—amici
  • greco—greci
  • porco—porci

Among nouns that are pronounced with the stress on the third-to-last syllable, there are many more exceptions:

  • carico—carichi
  • incarico—incarichi
  • abbaco—abbachi
  • valico—valichi
  • pizzico—pizzichi
  • strascico—strascichi
  • dialogo—dialoghi
  • catalogo—cataloghi
  • obbligo—obblighi
  • prologo—prologhi
  • epilogo—epiloghi
  • profugo—profughi

Finally, some nouns have both forms:

  • chirurgo—chirugi, chirurghi
  • farmaco—farmaci, farmachi
  • manico—manici, manichi
  • stomaco—stomaci, stomachi
  • sarcofago—sarcofagi, sarcofaghi
  • intonaco—intonaci, intonachi

Nouns ending in -ìo (with a stressed i) form regular plurals ending in -ìi:

  • zìo—zìi
  • pendìo—pendìi
  • rinvìo—rinvìi
  • mormorìo—mormorìi

NOTE: dìo becomes dèi in the plural.

  • Nouns ending in -ìo (with an unstressed i) lose the i of the stem in the plural, therefore ending in -i:
  • viaggio—viaggi
  • figlio—figli
  • coccio—cocci
  • raggio—raggi
  • bacio—baci
  • giglio—gigli

NOTE: tempio becomes templi in the plural.

Some nouns that end in -io in the singular, in the plural may be confused with other plurals of the same spelling; to avoid ambiguity are sometimes used, such as an accent on the stressed syllable, a circumflex accent on the ending, or on the final double i:

  • osservatorio—osservatori, osservatòri, osservatorî, osservatorii
  • osservatore—osservatori, osservatóri
  • principio—principi, princìpi, principî, principii
  • principe—principi, prìncipi
  • arbitrio—arbitri, arbìtri, arbitrî, arbitrii
  • arbitro—arbitri, àrbitri
  • assassinio—assassini, assassinî, assassinii
  • assassino—assassini
  • omicidio—omicidi, omicidî, omicidii
  • omicida—omicidi

Today the tendency is to write a single i without diacritical marks: the general meaning of the sentence usually resolves any doubt.

Some nouns ending in -o, which in the singular are masculine, in the plural become feminine grammatical gender and take the ending -a:

  • il centinaio—le centinaia
  • il migliaio—le migliaia
  • il miglio—le miglia
  • il paio—le paia
  • l'uovo—le uova
  • il riso (il ridere)—le risa

The table below summarizes the formation of the plural for Italian nouns ending in -o:

Plurale dei Nomi in -O








-co, -go (parole piane)

-chi, -ghi

-co, -go (parole sdruccioli)

-ci, -gì

-io (stressed i)


-io (unstressed i)


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Your Citation
Filippo, Michael San. "Formation of Italian Plural Nouns Ending in -O." ThoughtCo, Apr. 5, 2023, Filippo, Michael San. (2023, April 5). Formation of Italian Plural Nouns Ending in -O. Retrieved from Filippo, Michael San. "Formation of Italian Plural Nouns Ending in -O." ThoughtCo. (accessed May 28, 2023).