Contractions of de, em, a and por with articles

In brief

In Brazilian Portuguese, de, em, a, and por combine with a following definite article (o, a, os, as) into one word. Use the combined form whenever the noun takes that article: de + o becomes do, and em + a becomes na. The choice of ending follows the article’s gender and number, not the preceding word.

Form

de + o/a/os/as → do/da/dos/das; em + o/a/os/as → no/na/nos/nas; a + o/a/os/as → ao/à/aos/às; por + o/a/os/as → pelo/pela/pelos/pelas.

Usage

• Contract only when a definite article follows the preposition; de + o is do, but de + um remains de um.
• Keep the article’s gender and number: em + os becomes nos, while por + as becomes pelas.
• In ordinary writing, use the single combined form rather than writing the preposition and article separately.

Examples

• O livro é do professor. — The book belongs to the teacher.
• O livro está na mesa. — The book is on the table.
• Dou o livro ao professor. — I give the book to the teacher.
• Ele paga pelo almoço. — He pays for lunch.

Common mistake

❌ O livro é de o professor.

✅ O livro é do professor.

English keeps ‘of’ and ‘the’ separate, but Portuguese combines de + o into do.

Remember

First check whether the next noun has a definite article. If it does, combine that article with de, em, a, or por.