Portuguese loves to create new nouns by joining two words together. One of the most common recipes is taking a verb and attaching a noun to it. While English often uses two nouns for this (like "car trunk") or a single specialized word (like "corkscrew"), Portuguese clearly describes what the object does.
For example, a corkscrew pulls out corks, so it is called a saca-rolhas. A sunshade guards against the sun, making it a guarda-sol. These compounds are very common, but their spelling and grammar rules can be tricky for English speakers, especially when it comes to plurals and gender.
These words are formed by using a verb in the third person singular (the "he/she/it" form) followed by a noun. Because these words describe an object performing an action, they are generally masculine.
You will see this pattern in many everyday objects. An umbrella guards you from the rain, so it is a guarda-chuva. A bottle opener is an abre-garrafas. A hummingbird kisses flowers, making it a beija-flor.
Esqueci-me do guarda-chuva e agora está a chover.
(I forgot my umbrella and now it is raining.)
Onde puseste o saca-rolhas?
(Where did you put the corkscrew?)
O carro tem um para-brisas novo.
(The car has a new windshield.)
The plural rule for objects
The biggest hurdle with these words is figuring out how to make them plural. The rule of thumb depends entirely on the noun part of the compound.
Many of these objects interact with multiple things. A car trunk holds suitcases (malas), a glove box holds gloves (luvas), and a dishwasher washes dishes (louças). As a result, the Portuguese words for these objects end in a plural noun: porta-malas, porta-luvas, and lava-louças.
Because the second half of the word is already plural, the word itself does not change at all in the plural. You do not add any extra letters. Instead, you only change the article before it. One bottle opener is o abre-garrafas, and two bottle openers are os abre-garrafas.
Temos de comprar dois lava-louças para o restaurante.
(We have to buy two dishwashers for the restaurant.)
Os hóspedes deixaram as malas nos porta-malas dos táxis.
(The guests left their bags in the trunks of the taxis.)
However, if the noun part is singular, it behaves like a normal word and gets pluralized. Therefore, guarda-chuva becomes guarda-chuvas, and beija-flor becomes beija-flores.
As crianças abriram os guarda-sóis na praia.
(The children opened the parasols at the beach.)
Compounds for people and professions
While compound objects are almost always masculine, some verb and noun compounds describe people. Common examples include a bodyguard (guarda-costas) or a lifeguard (salva-vidas).
When the word refers to a human, it drops the "always masculine" rule. The gender of the word simply matches the gender of the person you are talking about. You can have o guarda-costas (male bodyguard) or a guarda-costas (female bodyguard). Because these specific examples already end in an "s", they stay exactly the same in the plural too.
A presidente contratou uma guarda-costas excelente.
(The president hired an excellent bodyguard.)
Os salva-vidas avisaram os nadadores sobre as ondas.
(The lifeguards warned the swimmers about the waves.)
Summary
Portuguese creates many compound words by combining a verb and a noun. When these refer to objects, they are almost always masculine. The most important rule to remember is that if the noun part already ends in an "s" (like porta-malas or saca-rolhas), the word stays the same in the plural, and only the article changes (os porta-malas).
Verb and noun compound words