Learn Portuguese (Portugal): A segunda reunião começa às dez horas. - The second meeting starts at ten o'clock.

Ordinal numbers act like adjectives and must agree with the noun they modify in both gender and number. Because reunião (meeting) is a feminine singular noun, the ordinal number must take the feminine singular form segunda.

Does the ordinal number segunda always go before the noun?

Yes! Unlike most descriptive adjectives in Portuguese, which usually come after the noun (like a color or size), ordinal numbers like segunda (second) or primeiro (first) almost always come before the noun they modify.

Is there a rule to know that reunião is a feminine word?

Words ending in -ão can be either masculine or feminine, which can be tricky to remember. However, almost all nouns ending in -ião (like reunião), -ção, or -são are feminine. That is why it takes the feminine article A and the feminine ordinal segunda.

Why do we use às instead of just a to say "at" ten o'clock?

When stating what time an event happens, Portuguese combines the preposition a (at) with the feminine plural article as (the). We need the plural article because horas (hours) is a feminine plural word. This combination creates the contraction às.