Frequency adverbs indicate how regularly an action occurs and help place habits, repetition, and constancy in the sentence. In Portuguese, they are invariable and do not change gender or number, as Adverbs of Time and Adverbs of Place. The most common list includes always, never, frequently, rarely, sometimes, and from time to time.

Always expresses total occurrence, never expresses total absence, and frequently, rarely, sometimes, and from time to time organize intermediate degrees of repetition. These forms can appear with a more formal or a more colloquial value, and 'from time to time' is a widely used adverbial phrase in informal register. When frequency is specified by a larger expression, such as every week, this expression also functions as an adverb of frequency.

IdeiaIdea	ExemploExample
sempre indica repetição totalAlways indicates total repetition	Eu sempre acordo cedo.I always wake up early.
nunca indica ausência totalNever indicates total absence	Ele nunca chega atrasado.He never arrives late.
frequentemente indica alta regularidadeFrequently indicates high regularity	Nós frequentemente jantamos fora.We frequently dine out.
raramente indica baixa regularidadeRarely indicates low regularity	Ela raramente assiste televisão.She rarely watches television.
às vezes indica ocorrência ocasionalSometimes indicates occasional occurrence	Às vezes estudamos na biblioteca.Sometimes we study in the library.
de vez em quando indica repetição esporádicaFrom time to time indicates sporadic repetition	De vez em quando chove à tarde.From time to time it rains in the afternoon.
todas as semanas funciona como advérbio de frequênciaEvery week functions as an adverb of frequency	Eles viajam todas as semanas.They travel every week.

In affirmative sentences, the frequency adverb is usually placed before the main verb, bringing it closer to the action's nucleus. In compound tenses, it tends to appear between the auxiliary and the participle, though the order can vary in more complex constructions. For a broader view of the order of elements, it is helpful to relate this use to Placement of Adverbs.

IdeiaIdea	ExemploExample
antes do verbo principal em frases afirmativasbefore the main verb in affirmative sentences	Eu sempre estudo depois do jantar.I always study after dinner.
entre auxiliar e particípio em tempos compostosbetween auxiliary and participle in compound tenses	Ela tem frequentemente visitado a família.She has frequently visited the family.
a frequência fica mais próxima do verbo do que do tempothe frequency stays closer to the verb than to the time marker	Nós raramente saímos ontem à noite.We rarely went out last night.

Never can substitute 'not' to negate the clause when the idea is repeated or absolute absence. The sequence 'not never' is redundant in standard usage, although it may appear in colloquial speech with emphatic value. In negative constructions, the position of never maintains the reading of strong negation and can reinforce the totality of refusal.

IdeiaIdea	ExemploExample
nunca pode substituir nãoNever can substitute 'not' to negate the clause when the idea is repeated absence or absolute.	Eu nunca fumo.I never smoke.
não nunca é redundante na norma geral'Not' never is redundant in standard usage	Ele nunca aceita ajuda.He never accepts help.
na fala coloquial a duplicação pode ter ênfaseIn colloquial speech, duplication may carry emphasis	Eu não vou nunca esquecer isso.I won't ever forget this.

Adverbs of intensity can modify adverbs of frequency to increase or decrease the degree of perceived regularity. 'Very' and 'quite' are common in this combination and reinforce the idea of habit, constancy, or recurrence. This relationship resembles the behavior of Adverbs of Intensity and Superlative Adverbs.

IdeiaIdea	ExemploExample
muito pode intensificar a frequênciaVery can intensify frequency	Eu muito frequentemente trabalho à noite.I very frequently work at night.
bastante pode intensificar a frequênciaQuite can intensify frequency	Ela bastante raramente falta às aulas.She quite rarely misses classes.
a intensidade modifica o grau de regularidadeThe intensity modifies the degree of regularity	Eles sempre estudam muito.They always study a lot.

When several adverbial modifiers appear, the frequency expression tends to be closer to the verb than to temporal or locative markers. Thus, the sentence usually organizes the habitual action first and then the time or place framing, which helps to keep the reading clear. In more complex uses, the position can vary between European Portuguese and Brazilian Portuguese, especially with compound tenses and emphatic focus.

IdeiaIdea	ExemploExample
a frequência fica mais perto do verbo que o tempoThe frequency stays closer to the verb than to the time	Eu sempre estudo de manhã.I always study in the morning.
o marcador temporal vem depois da frequênciaThe time marker comes after the frequency	Ela raramente trabalha à noite.She rarely works at night.
a ordem pode variar em estruturas complexasThe order can vary in complex structures	Eles frequentemente têm viajado para Lisboa.They frequently travel to Lisbon.

Frequently and rarely sound more formal, while 'from time to time' is very common in everyday speech. Always and never belong to general usage and cross distinct registers without changing form. The choice of expression depends on the desired effect, the degree of precision, and the tone of the communicative situation.

RegiãoRegion	Palavra ou ExpressãoWord or Expression	Definição RegionalRegional Definition	ExemploExample
FormalFormal	frequentementefrequently	Marca alta regularidade em registro mais neutro ou formal.Marks high regularity in a more neutral or formal register.	Eu frequentemente leio antes de dormir.I frequently read before going to bed.
FormalFormal	raramenterarely	Marca baixa regularidade e é comum em textos mais cuidados.Marks low regularity and is common in more carefully written texts.	Nós raramente interrompemos a aula.We rarely interrupt the class.
InformalInformal	de vez em quandofrom time to time	Marca ocorrência ocasional e é muito usada na conversa.Marks occasional occurrence and is very common in everyday speech.	De vez em quando ele aparece sem avisar.From time to time he shows up without warning.
GeralGeneral	sempre e nuncaalways and never	Expressam totalidade de frequência e funcionam em vários registros.Express the totality of frequency and span across registers.	Ela sempre responde; ele nunca demora.She always answers; he never takes long.

Adverbs of frequency are invariable and serve to measure the regularity of an action with the precision of habit, constancy, or eventuality. In general, they occupy a position close to the verb, can combine with intensifiers, and, in compound tenses, tend to stay between the auxiliary and the participle. The opposition between always and never, the nuance of sometimes and from time to time, and the difference in register between more formal and more informal forms show how frequency shapes the meaning of the sentence.