isso

Isso is a demonstrative pronoun in Portuguese used to refer to a thing or idea that is not near the speaker and that has been mentioned or is understood from context. It functions roughly as "that" or "this" in English, depending on usage, and it is neuter in form, not inflected for gender.

In contrast to isto (which often refers to things close to the speaker) and aquilo (which refers to something distant or less immediately relevant), isso typically points to a thing or situation known to both speaker and listener. Brazilian Portuguese uses isso widely in everyday speech, while European Portuguese more commonly prefers isto for near referents, with isso remaining common for referents not close to the speaker or listener. Aquilo remains the general choice for distant referents. Expressions such as isso aí or isso mesmo are common intensifiers or confirmations in conversation.

Grammatically, isso is a pronoun that can serve as subject or object and can pair with predicates to form statements like Isso é importante, or with verbs of thinking or speaking: Não sei o que é isso. It does not agree in gender, since it is a neuter demonstrative. It often appears in fixed phrases and colloquial constructions, and it is frequently used to introduce summaries or responses to prior discourse.

Etymology traces isso to the demonstrative series of Old Portuguese, related to other Romance forms such as Spanish eso and French cela. The word has remained a versatile, widely used part of everyday Portuguese syntax and discourse.