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Irregular plurals: 'uomini', 'dei', 'buoi' and other surprises

Most Italian plurals follow a few tidy vowel rules: -o becomes -i, -a becomes -e, -e becomes -i. A small group of very common nouns ignores these rules. Uomo becomes uomini, dio becomes dei and even takes a different article, bue becomes buoi, and tempio suddenly grows an extra letter in templi.

English speakers already know irregular plurals like men, mice and oxen, so the idea is familiar. The problem is that the Italian regular rules are so reliable that learners apply them on autopilot and produce forms like uomi or le ale. These words are few, so the best strategy is simply to learn each plural together with its article.

Word list
uomomA1 man l'uomo → gli uomini diomA2 god il dio → gli dei uomo d'affarimA2 businessman l'uomo d'affari → gli uomini d'affari alafB1 wing l'ala → le ali ala di pollofB1 chicken wing l'ala di pollo → le ali di pollo armafB1 weapon l'arma → le armi gentiluomomB1 gentleman il gentiluomo → i gentiluomini tempiomB1 church il tempio → i templi uomo politicomB1 politician l'uomo politico → gli uomini politici arma nuclearefB2 nuclear weapon l'arma nucleare → le armi nucleari buemB2 ox il bue → i buoi nobiluomomB2 nobleman il nobiluomo → i nobiluomini ecofC2 echo l'eco → gli echi
How it works

There is no hidden rule that produces these forms. They are leftovers from Latin and older Italian. They fall into a few rough types:

New syllables or other changes to the word

uomo → uomini, bue → buoi, tempio → templi.

A changed article as well

il dio → gli dei, even though dei starts with a consonant.

Feminine nouns in -a that take -i

l'ala → le ali, l'arma → le armi, where you would expect -e.

The rule of thumb is to memorize the singular and plural as a pair, article included: l'uomo, gli uomini, il dio, gli dei.

The words

Uomo is the most important one. Its plural uomini adds a whole syllable. Words built on it do the same: gentiluomo becomes gentiluomini and nobiluomo becomes nobiluomini.

Gli uomini e le loro mogli sono arrivati.
(The men and their wives have arrived.)
Nel romanzo ci sono molti gentiluomini inglesi.
(There are many English gentlemen in the novel.)
I nobiluomini vivevano nei palazzi del centro.
(The noblemen lived in the palaces in the center.)

Dio changes both the word and the article: il dio, but gli dei. With a capital letter, Dio means God and normally has no plural.

I Greci credevano in molti dei.
(The Greeks believed in many gods.)
Gli dei vivevano sull'Olimpo.
(The gods lived on Olympus.)

Tempio adds an l in the plural: i templi. The form tempi exists too, but it is the plural of tempo and means times.

A Roma abbiamo visitato due templi antichi.
(In Rome we visited two ancient temples.)

Bue becomes buoi, a form you simply have to learn by heart.

Il contadino ha due buoi nella stalla.
(The farmer has two oxen in the barn.)

Ala and arma are feminine and end in -a, yet their plurals end in -i. The article stays feminine: le ali, le armi.

L'uccellino apre le ali e vola via.
(The little bird opens its wings and flies away.)
La polizia ha trovato le armi in una cantina.
(The police found the weapons in a basement.)
Watch out

Eco is the strangest case. In the singular it is usually feminine, l'eco or una eco, but the plural is masculine: gli echi. The h keeps the hard sound, as in amico, but the gender switch is the real surprise.

In montagna si sentono gli echi delle nostre voci.
(In the mountains you can hear the echoes of our voices.)

Watch out for these typical mistakes:

  • gli uomi or gli uomo instead of gli uomini.
  • i dei instead of gli dei.
  • le ale and le arme instead of le ali and le armi.
  • i tempi when you mean temples. Say i templi.

Some plurals only look odd. Moglie → mogli is regular, since final -e simply becomes -i. The same goes for spelling changes like ciliegia → ciliegie or valigia → valigie, which follow a spelling rule rather than being true irregulars.

Summary

A handful of common nouns form their plural in ways no rule predicts: uomo → uomini (also gentiluomini, nobiluomini), il dio → gli dei, bue → buoi, tempio → templi, ala → ali, arma → armi, and l'eco → gli echi. Learn each one as a singular and plural pair with its article, and don't let the regular vowel rules take over.