The nominal augmentative is a device to indicate a large size or intensified value of a noun, without relying on comparative contexts. In Portuguese, the augmentative can be formed by suffixes, by analytic construction with words such as 'grande', or by irregular and conventionalized forms through usage. The augmentative can also carry affective or evaluative meanings, such as exaggeration, admiration, or criticism, depending on the context.

The suffix -ão is the most frequent regular augmentative for common and concrete nouns in Portuguese. It attaches to the noun's stem and can cause simple orthographic adjustments, such as keeping or removing vowels. The use of -ão tends to form words with a sense of physical size or intensity, potentially acquiring evaluative tones from the context. Not every noun accepts -ão naturally, and some become uncommon or acquire a pejorative sense when forced.

The suffix -ona forms augmentatives with feminine marking and is productive for feminine nouns and for gender‑varying nouns. It can also appear in masculine forms as an expressive variation, but generally competes with -ão for the masculine. In many cases, -ona strengthens the idea of size together with an expressive effect, which can sound more marked, affective, or pejorative depending on the word and the tone. The choice between -ão and -ona depends on the gender of the noun and on the conventions of language use.

The synthetic augmentative is formed by a suffix in a single word, such as casarão or mulherona. It follows derivation rules and typically preserves the basic sense of the noun, enlarging size or intensity. In many cases, the synthetic augmentative creates lexicalized forms that approach new nouns with their own uses. Some synthetic augmentatives may compete with ironic diminutives in expressive terms, but they continue to function as a morphological augmentative.

The analytic augmentative occurs when the noun is accompanied by an adjective or expression that indicates largeness, such as 'large' or 'of size'. This construction is flexible and allows specifying the type of largeness, such as weight, height, or volume. The analytic is common when the speaker wants clarity or a determinate degree, without a strong expressive effect. In many contexts, the analytic coexists with the synthetic, and the choice depends on emphasis and naturalness of the sentence.

Some augmentatives have become established in usage with distinct or predominant senses, functioning almost as independent words. In these forms, the meaning can include largeness, but also additional semantic traits such as function or type. Memorization of these forms is part of the domain of the augmentative in the lexicon, because they are not always explained by the suffix rule alone. In dictionaries and in formal use, these words may appear as autonomous items while being recognized as augmentatives.

Some nouns form augmentatives with internal changes or irregular choices, by language tradition. In some cases, the resulting form may change gender, accentuation, or structure, not fully following the regular pattern. There are also nouns that prefer the analytic due to usage, even though they are theoretically possible with the suffix. Recognizing these irregularities helps prevent misinterpretations or forms that sound unnatural.

The augmentative can change its semantic effect according to context, alternating between a literal sense of size and an evaluative sense. In many cases, the augmentative expresses admiration, surprise, or criticism, depending on the speaker's intention. Certain augmentative words tend to sound more pejorative or jocular through conventional usage, not just morphology. The appropriate interpretation depends on the complete utterance and the communication situation.

The nominal augmentative in Portuguese is based mainly on the suffixes -ão and -ona to indicate largeness, with variation by gender and expressiveness. Synthetic and analytic forms coexist, and the choice involves clarity, emphasis, and naturalness. There are fixed augmentatives and irregularities that should be memorized as part of the lexicon. The final meaning of the augmentative depends on context, and can range from literal to evaluative.