Irregular Comparative: MAU/RUIM → PIOR

Most Portuguese adjectives follow a simple rule for comparisons. You just add mais (more) before the adjective. For example, mais feliz (happier). However, a small group of adjectives are rebels. They are called irregular comparatives. Mau (bad) and ruim (bad/poor quality) are the leaders of this rebel group. When you want to compare two things, they both transform into pior. Think of pior as a shortcut. It combines the idea of "more" and "bad" into one single package. This word is gender-neutral. It stays the same whether you are talking about a man, a woman, a car, or a house. It does, however, have a plural form, which we will look at later. It is a very efficient way to express dissatisfaction.

1. 1Using pior is actually easier than using regular adjectives. You don't have to worry about matching the gender of the noun. Here is how you build a sentence with it:
2. 2Start with the first thing you are talking about (the subject).
3. 3Add the verb, usually ser (to be) or estar (to be/feel).
4. 4Insert the word pior.
5. 5Add do que or just que to mean "than."
6. 6End with the second thing you are comparing it to.
7. 7For example: Este livro (This book) + é (is) + pior (worse) + do que (than) + o outro (the other one). It is a straight line from point A to point B. No complex gymnastics required. Even if you are talking about multiple things, the only change is adding an "es" to the end: piores.

Use pior whenever you are comparing two specific entities. Imagine you are at a restaurant. The soup today is cold and salty. You might say it is pior than the soup you had last week. Or imagine you are in a job interview. You might talk about a pior scenario you handled in the past. It is perfect for:

• Comparing quality: Este carro é pior. (This car is worse.)
• Comparing situations: A chuva está pior agora. (The rain is worse now.)
• Comparing health: Eu me sinto pior hoje. (I feel worse today.)
• Comparing performance: O time jogou pior hoje. (The team played worse today.)

It is a versatile word that fits into casual chats and formal reports alike. It is the universal "thumbs down" of Portuguese grammar.

Don't use pior if you aren't actually comparing two things. If something is just "very bad" but not necessarily "worse than something else," you might prefer muito mau or péssimo. Also, avoid using mais with pior. Saying mais pior is a classic mistake that will make native speakers cringe. It is like saying "more worse" in English. It’s redundant and sounds a bit uneducated. Think of pior as already having the "more" built inside of it. You also shouldn't use it to mean "the worst" in a superlative sense without an article like o or a. Pior on its own is for comparing A to B. If A is the bottom of the barrel out of everyone, that is a slightly different structure.

Yes, even native speakers mess this up sometimes, but you don't have to! The biggest trap is saying mais ruim or mais mau. While you might hear mais ruim in very informal Brazilian Portuguese, it is technically incorrect in standard grammar. Another mistake is forgetting the plural. If you are comparing two sets of things, like estes sapatos (these shoes), you must use piores. Estes sapatos são piores. Don't let the gender-neutral nature of the word trick you into thinking it never changes at all. Lastly, watch out for the do que vs que choice. Both are fine, but beginners often forget the que entirely, which leaves the sentence hanging.

It helps to look at pior alongside its siblings. The most famous sibling is melhor (better), which comes from bom (good). They follow the exact same logic. Just as bom becomes melhor, mau becomes pior. They are two sides of the same coin. You also have maior (bigger) from grande and menor (smaller) from pequeno. All these irregulars share the same trait: they don't use mais. If you can master pior, you have essentially mastered the entire category of irregular comparatives. It’s a "buy one, get four free" deal for your brain.