Compound Words

Compounding is the other great word-building strategy alongside suffixation: instead of adding a morpheme to a base, you fuse two whole words into one. Brazilian Portuguese does this in two visibly different ways — juxtaposition, where both words stay recognizable (often joined by a hyphen, as in guarda-chuva), and agglutination, where the words fuse and lose sounds (planalto from plano + alto). Knowing which is which explains both the spelling and — trickily — how the word forms its plural. For the compound nouns as vocabulary, see compound nouns; this page is about the morphological process.

Two ways to compound

The distinction is structural, not decorative.

• Juxtaposition (justaposição) places two words side by side with no phonetic change. Each element keeps its own form and stress. The join is shown by a hyphen or, increasingly, by writing them as one solid word (girassol, passatempo) or as separate words. Examples: couve-flor (cauliflower), guarda-chuva (umbrella), beija-flor (hummingbird).
• Agglutination (aglutinação) fuses the elements with phonetic loss — a vowel or syllable disappears at the seam, and there is a single stress. Once fused, the parts may no longer be obvious. Examples: planalto (< plano + alto, plateau), pernalta (< perna + alta, long-legged), embora (< em boa hora), fidalgo (< filho de algo, nobleman), vinagre (< vinho + acre).

The main structural types

Compounds are classified by the parts of speech they combine. The most productive type by far in Portuguese is verb + noun, which forms agent-or-instrument nouns (literally "thing that Xs the Y").

The verb+noun pattern is alive and coining new words: quebra-mola (speed bump), limpa-vidros (window cleaner), porta-aviões (aircraft carrier — "carries-planes"). Note the verb stays in a fixed third-person singular form and never agrees with anything.

Coordinate vs. subordinate compounds

A further distinction governs meaning and, again, plurals. In a subordinate compound, one element modifies the other (a peixe-espada is a kind of peixe shaped like a espada — the espada describes the fish). In a coordinate compound, the two elements are equals, neither subordinate (a surdo-mudo, deaf-mute, is equally deaf and mute). This matters because coordinate compounds typically pluralize both elements, while subordinate ones often pluralize only the head.

Hyphenation after the 1990 Orthographic Agreement

The 1990 reform (AO90), in force in Brazil, kept the hyphen in most lexical compounds but tidied the rules. Key points for compounds:

• Compounds whose elements keep their identity and form a single concept generally retain the hyphen: guarda-chuva, segunda-feira, bem-vindo, couve-flor, amor-perfeito.
• When the speaker no longer perceives the compound as two words, it is written solid, no hyphen: girassol (sunflower), paraquedas (parachute — the reform removed the old hyphen), mandachuva (big shot), passatempo (pastime), pontapé (kick).
• Compounds with animal/plant names and those denoting a single botanical or zoological species keep the hyphen: bem-te-vi (a bird), couve-flor.

For the full hyphen system (prefixes, repeated letters, etc.), see hyphenation rules.

Pluralizing compounds — the part most learners fear

There is no single rule, but the structure tells you what to do. Work through these cases:

The logic: in verb + noun compounds, the verb is frozen (it never agrees with anything), so only the noun can show plural — os guarda-roupas, os quebra-cabeças. In noun + noun / noun + adjective, both are real nouns/modifiers and both can agree — couves-flores. And once a compound has agglutinated into a single opaque word, it inflects like any ordinary noun — planaltos, pontapés, paraquedas (invariable because it already ends in -s).

English comparison

English compounds far more freely than Portuguese but almost always by simple juxtaposition with no hyphen and no internal inflection: toothbrush, raincoat, bus driver. English never agglutinates with sound loss the way planalto does, and it never pluralizes an internal element — you say toothbrushes, never *teethbrushes. Portuguese, by contrast, may inflect inside the compound (couves-flores), which is the single most counterintuitive point for English speakers. Also, where English strings nouns together loosely (kitchen table), Portuguese usually prefers a prepositional phrase (mesa de cozinha) rather than a true compound — so don't assume every English compound has a one-word Portuguese twin.

Common Mistakes

Key Takeaways

• Compounds form by juxtaposition (elements intact: guarda-chuva) or agglutination (elements fused with sound loss: planalto < plano + alto).
• The verb + noun type is the most productive (guarda-roupa, quebra-cabeça, porta-aviões); the verb is frozen.
• Under AO90 most lexical compounds keep the hyphen, but opaque ones go solid (paraquedas, girassol, passatempo).
• Plurals follow structure: verb+noun pluralizes only the noun; noun+noun/noun+adjective pluralizes both; agglutinated words inflect as single words.
• Unlike English, Portuguese can inflect inside a compound (couves-flores) and often prefers de-phrases over bare noun stacking (mesa de cozinha).