Ordinal numbers

The First Ten (the only ones you really need)

These are the ordinals Brazilians use every day:

Floors & addresses

• "Moro no quinto andar." (I live on the fifth floor.)

• "O escritório fica no terceiro andar." (The office is on the third floor.)

• "A segunda porta é a cozinha." (The second door is the kitchen.)

• "No 11º andar, a gente fala andar onze." (For the 11th floor, we say "floor eleven.")

Ranking & competition

• "O Brasil está em primeiro lugar!" (Brazil is in first place!)

• "Ela é a terceira da fila." (She's third in line.)

• "Ficamos em segundo lugar." (We're in second place.)

Everyday life

Térreo: the floor that isn't "first"

In Brazil the ground floor is the térreo, not the primeiro andar. So the primeiro andar is already one flight up. A few newer buildings number the ground floor as 1º, so when it matters, just ask: "O térreo é o primeiro andar?"

"segundo" has three lives

The same word means three different things — context decides:

• segundo lugar = second place (ordinal)

• um segundo = a second of time (noun)

• segundo o João = according to João (preposition)

Centuries & monarchs: stop at ten

Just like floors — ordinal up to 10, cardinal after:

• "século vinte e um" (the 21st century) — not "vigésimo primeiro"

Here's a secret you already half-know: Portuguese is the only Romance language that counts its weekdays. Segunda-feira (Monday) is literally the "2nd feira," terça-feira the "3rd," on through sexta-feira (Friday) — everyday ordinals hiding in plain sight (terça is just an older form of terceira). The feira part comes from the Latin feria ("holy day"): early Christians numbered the days relative to Sunday — feria secunda, feria tertia — and the habit survived only in Portuguese.

Sources: Ciberdúvidas da Língua Portuguesa, Ciberdúvidas — Ainda a origem dos dias da semana