Plurals in Nouns and Adjectives by Fernanda L. Ferreira, Ph.D.
In formal written Portuguese and very formal speech, number agreement is followed pretty strictly. This does not happen in colloquial or less careful speech. Some words are easy to guess the plural, and others either follow a predetermined rule or are exceptions and must be learned by heart. Here are the rules for forming plural nouns in Portuguese.
First, as a general rule: add an — s to the singular form.
All the plural words in Portuguese end in — s. However, there might be changes to the previous vowels or consonants that come before. The plural formation depends on the stress of the words and whether diphthongs are found at the end.
If the word ends in — l, drop — l and add — is. If the result is — iis, drop one — i.
If the word ends in — l but the last syllable is not stressed, drop — l and add — eis.
If the word ends in — s or — x, and the last syllable is not stressed, the plural is identical.
If the word ends in — m, drop — m and add — ns.
If the word ends in a consonant, add — es.
The words in the next group end in — ão in the singular and have three different possibilities in the plural. Here is how this works:
If the word ends in — ão, and the last syllable is not stressed, add — s.
If the word ends in — ão and the last syllable is stressed, add — s, or — ões, or — ães:
The first example (irmãos) shows the simple “add an — s” rule. However, this is not the most common plural for words ending in — ão. The second example (melões) is actually the most common result for the singular words that end in — ão. If one had to guess the plural of a word ending in — ão, this would be the best guess. Finally, the last example (capitães) is the least common case. There are only a handful of words in Portuguese that have this plural ending, including pães (breads) and alemães (Germans). Even though it might seem daunting at first, plurals are manageable in Portuguese once you learn the general rules.
Exercise: What's the Plural Form?
Now let's see what you've learned about singular and plural forms of words in Portuguese. Write the plural forms of the following words in Portuguese. Check your answers in Appendix C.