Portuguese makes a clear distinction between the different word classes, that include verbs, nouns, pronouns, adjectives, adverbs, prepositions, articles, conjunctions and interjections. There are also some other determiners and particles.
Verbs are divided into three conjugations, which can be identified by looking at the infinitive ending, one of "-ar", "-er", "-ir" and "-or", which is present in a small number of verbs ,like "pôr" (to put). Most verbs end with "-ar", such as cantar (to sing). All verbs with the same ending follow the same pattern, save irregulars.
In Portuguese, verbs appear in distinct moods:
~ Imperative, used to express wish, command or advice.
~ Indicative, used in the main clauses of declarative sentences.
~ Subjunctive (conjuntivo). Used to express the content of a wish, a possibility or, in subordinate clauses, something denied in the main clause.
~ Conditional, which is described as a distinct mood in some grammars, mostly in Portugal, less frequently in Brazil.
Along with moods, there are non-finite verb forms:
~ Past participle (or passive participle)
There is no present or active participle in Portuguese, but many adjectives come from Latin present participles and carry more or less the same meaning. Some neologisms are created in the same pattern. Unlike English, these "present participles" are not identical in form with gerund.
Portuguese subjunctive mood has almost as many tenses as the indicative, namely present, perfect, imperfect, pluperfect and future, not mentioning periphrastic structures. In regular verbs, subjunctive future, which is uncommon in Indo-European languages, is identical to personal infinitive, but not in irregular verbs. And its role is obviously very different.
Portuguese conditional mood is often described as a tense, namely the "future of the preterite". It has two forms, that can be rendered as the "future of the (perfect or imperfect) past" (for instance iria, would go) and the "future of the pluperfect" (for instance teria ido, would have gone). Periphrastic structures provide other tenses. Conditional is found more often in formal than in informal speech, where it is commonly replaced by the imperfect tense.
Another interesting feature of Portuguese verbs is the existence of two or three equivalent forms for some past tenses, either in the indicative or in the subjunctive, but something similar happens in French and Spanish perfect tenses. For instance, in the indicative pluperfect it is possible to use either the auxiliary verbs ter (from Latin tenere) and haver (from Latin habere) or a simple form. He had gone could be translated either as Ele tinha ido, Ele havia ido or Ele fora. The two latter options, however, are much less common in oral and informal languages. The simple form (fora) would be sometimes seen as archaic or literary.
All Portuguese nouns have one of two genders: masculine or inclusive and feminine or exclusive. Most adjectives and pronouns, and all articles indicate the gender of the noun they reference. The feminine gender in adjectives is formed in a different way from that in nouns. Most adjectives ending in a consonant remain unchanged: homem superior (superior man), mulher superior (superior woman). This is also true for adjectives ending in "e": homem forte (strong man), mulher forte (strong woman). Except for this, the noun and the adjective must always be in agreement: homem alto (tall man), mulher alta (tall woman).