Adjectives- Adjectives of Plural Nouns
The rules for constructing adjectives of Portuguese plural nouns from singular adjectives are similar to the formation of Portuguese plural nouns from singular nouns.
If the singular adjective ends with a vowel, add -s.
If the singular adjective ends with a consonant, add -es.
- Exception: If the singular adds with -m, add -ns.
- Exception: If the singular adds with -l, add -is.
- Exception to the exception: If the singular adds with -il:
- Change -il to -is if the last syllable is stressed.
- Change -il to -eis if the last syllable is unstressed.
It singular ends with -ão, there are three possible endings for the plural, and since they are arbitrary, they must be learned by memorization.
gato grande (big cat)
gatos grandes (big cats)
gato feliz (happy cat)
gatos felizes (happy cats)
gato honesto (honest cat)
gatos honestos (honest cats)