Interjections are words with an emotive function. They are used to express emotions, sensations, and moods. They can be just simple vowel sounds, like «Ah!» and «Oh!», but most are either a free word or a phrase, in which case, we call them locuções interjetivas.
The same interjeição can have different meanings depending on the context in which it appears, its purpose, and the speaker’s attitude. Even with simple vowel sounds, sometimes changing the tone and extending the sound will give it another meaning.
Ai! Bati com o joelho na mesa.Ah! I hit the table with my knee.
Ai! Já me estou a passar contigo.Ah! You’re getting on my nerves.
Interjections can be used as a standalone reply / affirmation or they can be followed by a sentence.
Irra! Vocês não conseguem mesmo estar calados, pois não?Geez! You really can’t keep quiet, can you?
There’s practically an unlimited number of interjeições, but below you will find the most common grouped by meaning/context.