Italian Ordinal Numbers

Italian ordinals — primo, secondo, terzo — answer the question "in what position?" rather than "how many?". They tell you which floor you live on, which century a painting belongs to, which pope is which, and the date of New Year's Day. Unlike cardinals, which are largely invariable, ordinals are full adjectives: they inflect for both gender and number and they sit before the noun in their default position. Once you have the first ten memorised, the rest of the system is mechanical — you bolt the suffix -esimo onto any cardinal and you're done.

This page covers the forms (the irregular first ten and the productive -esimo construction), the agreement rules, and the four contexts where ordinals carry a meaning that English speakers consistently get wrong: dates, centuries, monarchs, and discourse markers.

The first ten: irregular and worth memorising

The ordinals from primo to decimo descend from Latin and have no shared root with the Italian cardinals — they are independent words that must be learned by heart. After that, the system becomes regular.

Several of these you already know from other contexts — quarto shows up in time-telling (un quarto d'ora), terzo in il Terzo Mondo, primo in primo piatto (the pasta course of an Italian meal). Knowing the ordinal as a building block of everyday vocabulary makes it easier to retain.

From eleven onward: the -esimo machine

Starting at eleven, Italian builds ordinals with a single, predictable rule: drop the final vowel of the cardinal and add -esimo.

• undici → undic-
  • -esimo = undicesimo (11th)
• dodici → dodic-
  • -esimo = dodicesimo (12th)
• tredici → tredic-
  • -esimo = tredicesimo (13th)
• quattordici → quattordicesimo (14th)
• quindici → quindicesimo (15th)
• sedici → sedicesimo (16th)
• diciassette → diciassettesimo (17th)
• diciotto → diciottesimo (18th)
• diciannove → diciannovesimo (19th)
• venti → ventesimo (20th)
• trenta → trentesimo (30th)
• cento → centesimo (100th)
• mille → millesimo (1000th)

The exception that isn't: -uno and -tré endings

Compound numbers ending in -uno or -tré (21, 31, 41... 23, 33, 43...) keep the full final vowel before -esimo, because dropping it would create an unpronounceable cluster:

• ventuno → ventunesimo (21st) — keep the -o of uno
• ventidue → ventiduesimo (22nd)
• ventitré → ventitreesimo (23rd) — note: -tré loses its accent when -esimo attaches, because the stress moves
• trentuno → trentunesimo (31st)
• quarantuno → quarantunesimo (41st)

This is the only wrinkle in the entire system. Once you internalise it, every ordinal up to a million is predictable.

Agreement: ordinals are full adjectives

Unlike cardinals — which are invariable except for uno — ordinals inflect for gender and number like any four-form Italian adjective. Primo has the four shapes primo / prima / primi / prime; the same applies to every ordinal in the system.

The ordinal's default position is before the noun, exactly like other adjectives that express order or judgement (buono, bello, grande). Putting an ordinal after the noun is grammatical but rare and marked — used for emphatic contrast or in fixed titles (Carlo Quinto, Luigi Quattordicesimo).

Dates: the special role of primo

Here is the rule that trips up every English speaker: in Italian dates, the first day of the month uses the ordinal, but every other day uses a cardinal.

• 1 January → il primo (di) gennaio
• 2 January → il due (di) gennaio
• 15 March → il quindici (di) marzo
• 31 December → il trentuno (di) dicembre

For full date formats — articles, prepositions, year, day-of-week — see dates.

Centuries: two ways to say "the 20th century"

Italian has two coexisting systems for naming centuries, and educated speakers use both.

The literal way uses the ordinal directly: il ventesimo secolo (the 20th century), il ventunesimo secolo (the 21st century), il diciannovesimo secolo (the 19th century). This is the bookish, modern, neutral form — the one you'll see in a history textbook or a museum caption.

The Italian way uses a centuries-old alternative: drop the "century" word, name the century after its hundreds, and capitalise it. The pattern works only for centuries from the 1200s through the 1900s.

The 21st century has no short form (il Duemila is sometimes used playfully for "the 2000s," but it's a different kind of word — referring to the round number 2000 itself, not a century in the same series). For the 21st century, use il ventunesimo secolo.

Monarchs and popes: ordinals in Roman numerals

When Italian writes a king's, queen's, or pope's name with a Roman numeral, the numeral is read aloud as an ordinal, even though the digit on the page looks like a cardinal.

• Giovanni XXIII → Giovanni ventitreesimo
• Carlo V → Carlo Quinto
• Luigi XIV → Luigi Quattordicesimo
• Elisabetta II → Elisabetta seconda
• Vittorio Emanuele III → Vittorio Emanuele terzo
• Papa Francesco I → Papa Francesco primo (when distinguishing from a hypothetical successor)

In this position the ordinal follows the name — the only common context where Italian ordinals appear after the noun without any special emphasis. You will hear them frequently if you watch any Italian historical documentary or news report on Vatican affairs.

Discourse markers: in primo luogo, in secondo luogo

Ordinals are also the building blocks of Italian discourse markers — the phrases you use to organise an argument or a list. The pattern is in + ordinal + luogo ("in the X-th place"), and it's perfectly idiomatic in writing and in formal speech.

In speech, simpler markers like primo... secondo... terzo (used as bare adverbials) are also common, especially in arguments and informal lists: Primo, non mi piace; secondo, costa troppo; terzo, non mi serve. The fuller in primo luogo register belongs to writing, lectures, and formal presentations.

Sports, rankings, and floors

Ordinals dominate the language of competition and physical position.

• primo posto, secondo posto, terzo posto — first, second, third place on a podium
• il piano terra (ground floor — Italian counts the ground floor as its own thing) and then il primo piano, il secondo piano, il terzo piano. An American "second floor" is the Italian primo piano. This is a frequent source of confusion.
• la prima fila, l'ultima fila — the front row, the back row (in a theatre or cinema)
• la prima media, la seconda media, la terza media — the three years of middle school in Italy

Common Mistakes

Key takeaways

1. The first ten ordinals (primo through decimo) are irregular and must be memorised. From eleven onward, the system is regular: drop the cardinal's final vowel and add -esimo.

2. Italian ordinals are four-form adjectives (primo / prima / primi / prime). They agree in gender and number, and they normally sit before the noun.

3. The first day of the month uses primo; every other day uses the cardinal. Centuries from the 1200s to the 1900s have a special capitalised short form (il Trecento, il Novecento).

4. Roman numerals after a sovereign's or pope's name are read as ordinals (Giovanni ventitreesimo), and the ordinal sits after the name in this fixed construction.

For the cardinals that ordinals are built from, see cardinals 0–20 and cardinals 21–100. For full date constructions, see dates.