Ordinal numbers

What are ordinal numbers?

• Cardinal numbers answer: “How many?” → uno, due, tre…
• Ordinal numbers answer: “Which one in order?” → primo, secondo, terzo…

In this unit, you learn ordinal numbers for order: floors, days, people in a queue, points in a meeting.

Key forms: 1st–10th at a glance

Rule 1 – Agreement: match the noun

Ordinal numbers work like adjectives. They must agree with the noun:

• Masculine singular: primo, secondo, terzo…
• Feminine singular: prima, seconda, terza…
• Masculine plural: primi, secondi, terzi…
• Feminine plural: prime, seconde, terze…

Self-check:

1. Identify the noun: masculine or feminine? singular or plural?
2. Choose the ordinal that matches those two features.

Examples:

• masc. sg. – il quinto tavolo (the fifth table)
• fem. sg. – la terza persona (the third person)
• masc. pl. – i secondi colloqui (the second interviews)
• fem. pl. – le quarte pagine (the fourth pages)

Rule 2 – Basic pattern after 10: the suffix -esimo

From 11th onwards, the regular form is:

• cardinal number stem + -esimo (for masculine)
• then change the ending for feminine / plural as usual

Important details:

• Drop the final vowel of the cardinal before -esimo.
  • undici → undicesimo, not *undici-esimo
  • venti → ventesimo, not *venti-esimo
• With compounds, the last part changes:
  • ventuno → ventunesimo
  • trentadue → trentaduesimo (32nd)

Rule 3 – Where does the ordinal go in the sentence?

Most often, the ordinal goes before the noun, like in English:

• il primo giorno (the first day)
• la terza riunione (the third meeting)
• il ventunesimo piano (the 21st floor)

Typical contexts at work:

• Floors: primo, secondo, terzo… piano
• Points in an agenda: primo, secondo, terzo punto
• People in a list: il primo candidato, la seconda candidata
• Days of the month: il primo aprile, il decimo giorno

Attention – “primo/prima” used alone

Sometimes the ordinal appears without a noun because the noun is clear from context.

• Parla per prima la direttrice.
  → “The director speaks first.” (per prima agrees with la direttrice)
• Chi è il secondo?
  → “Who is second?” (we know it’s the second candidate / person)

Self-check: ask yourself “Second what?” If the noun is obvious, Italian can drop it, but the ordinal still agrees in gender and number.

Common mistakes to avoid

• Mixing cardinal and ordinal:
  • *il ventuno piano → il ventunesimo piano
  • *il piano undici (as an order) → l’undicesimo piano
• Forgetting gender agreement:
  • *la terzo persona → la terza persona
  • *il seconda colloquio → il secondo colloquio
• Using Spanish-like forms:
  • *primero piano → primo piano

Mini steps: can you do these?

1. Say the floor of your office or home.
   • Formula: al / alll’ + [ordinal] + piano
   • Example: L’ufficio è al sesto piano.
2. Say the date of your birthday.
   • Formula: il + [ordinal] + (di) + mese
   • Example: Il mio compleanno è il primo di aprile.
3. Describe positions in a list of people.
   • Lui è il secondo nella lista.
   • Lei è la terza candidata.

If you can build and change these sentences correctly (masculine/feminine, singular/plural, -esimo forms), you have the essentials of Italian ordinal numbers for everyday and office situations.