Por que se usa o termo "simples (com plural)" em tudos os tempos ??
Hi everyone. These days I refer to the conjugation tables of Portuguese (PT) verbs from the book "Les verbes portugais -- formes et emplois", ISBN 978-2-218-93177-2, which is from the Bescherelle collection of the foreign-language series.

From there, I have found one thing that is quite confusing: Whenever they refer to a tense in "simple" form, they ALWAYS use "simples" (in plural form) but NOT "simple", even though it refers to simply a singular tense form. For instance,

simple past tense = pretérito perfeito simples
simple past pluperfect tense = pretérito mais-que-perfeito simples
simple future of present tense = futuro do presente simples
simple future of past tense = futuro do pretérito simples

Why is it expressed in such a way? I appreciate that someone may kindly explain the reasons. Many thanks in advance.

Question

Por que se usa o termo "simples (com plural)" em tudos os tempos ??
Hi everyone. These days I refer to the conjugation tables of Portuguese (PT) verbs from the book "Les verbes portugais -- formes et emplois", ISBN 978-2-218-93177-2, which is from the Bescherelle collection of the foreign-language series.

From there, I have found one thing that is quite confusing: Whenever they refer to a tense in "simple" form, they ALWAYS use "simples" (in plural form) but NOT "simple", even though it refers to simply a singular tense form. For instance,

simple past tense = pretérito perfeito simples 
simple past pluperfect tense = pretérito mais-que-perfeito simples 
simple future of present tense = futuro do presente simples 
simple future of past tense = futuro do pretérito simples

Why is it expressed in such a way?  I appreciate that someone may kindly explain the reasons.  Many thanks in advance.

Answer

Simples is invariable in Portuguese. It is equivalent to simple in English and, just like its counterpart in English, is used for both single and plural words. And there are some words in Portuguese end with an S but they are not plural. Being invariable, you will never see the word simples in Portuguese, even with words in the plural.

Answer

seems there's an echo in here..lol

Answer

Well, I have consulted some online multi-lingual dictionaries, and I have found that the term "simples" in Portuguese is invariable in singular or plural. Hence, this question was not well posted. Thanks very much for all the respondents who answered hereby. Good day. / Que tenha um bom dia.

Answer

A palavra «simples» mantém-se inalterável tanto se utilize no singular como no plural:

no singular:  Aquele vestido é simples.
no plural    : Aqueles vestidos são simples."

no singular : Pessoa simples, 
no plural fica : Pessoas simples
  

Classificação morfossintática:
- [simples] substantivo masc singular .
- [simples] substantivo masc plural .
- [simples] substantivo fem singular .
- [simples] substantivo fem plural .
- [simples] adjetivo masc singular .
- [simples] adjetivo masc plural .
- [simples] adjetivo fem singular .
- [simples] adjetivo fem plural .
 
1.   simples
  O que não é complicado, seja em aparência ou em personalidade, feito de poucas partes, sem *ocultar nada (*esconder). 
  
  Sem ornamentações (enfeites), ingênuo, modesto. 


Substantivos terminados em S
A) Palavras monossílabas ou oxítonas

Acrescenta-se ES. 

Exemplos

ás = ases deus = deuses ananás = ananases 

B) Palavras paroxítonas ou proparoxítonas: Ficam invariáveis. 

Exemplos

os lápis. os tênis os atlas 

Cuidado: Cais é invariável.

Answer

It's probably because the word "simple" doesn't exist in portuguese, hehe. The right spelling is "simples" with an "s" both in the singular and plural. 
E.g.: Esta frase é simples. Estes textos são simples. 
It's not just the names of tenses.

Qu'est ce qu'on ferait sans les Bescherelle franchement :P