O prejuízo foi grande.

O is the masculine singular definite article, meaning the.

In Portuguese, it is very common to use the definite article with nouns where English might also use the, and sometimes even where English would leave it out. In O prejuízo foi grande, the speaker is referring to a specific loss or damage that is understood from the context.

Without the article — Prejuízo foi grande — the sentence sounds unnatural in standard Portuguese.

Prejuízo is a masculine singular noun, so it takes o.

A learner may notice that it does not end in -o by accident: many masculine nouns do, and prejuízo is one of them. Its plural is prejuízos.

So:

• o prejuízo = the loss / the damage
• os prejuízos = the losses / the damages

Not exactly.

Both can refer to a loss, but prejuízo often sounds more like:

• financial loss
• damage
• harm
• disadvantage

Perda is broader and can be used for many kinds of loss, including emotional or physical loss.

For example:

• A empresa teve um grande prejuízo. = The company had a big financial loss.
• A perda do amigo foi difícil. = The loss of the friend was difficult.

So in many business or economic contexts, prejuízo is especially common.

Foi is the past tense of ser in the preterite. It presents the loss as a completed fact.

So O prejuízo foi grande means something like:

• the loss turned out to be large
• the loss was great

If you say O prejuízo era grande, that sounds more descriptive or backgrounded, as if you are setting the scene or talking about how things were at that time.

A simple way to think about it:

• foi = completed fact, event, conclusion
• era = description, background, ongoing past situation

Both can be correct, but they create different viewpoints.

Portuguese uses ser here because the sentence is identifying a characteristic of the loss: it was big/serious.

This is not a temporary physical state like something being open, closed, tired, or ready. It is more like assigning a quality to the loss.

That is why foi grande sounds natural.

Using estar here would normally sound wrong:

• O prejuízo esteve grande ✘

Because grande is working as a predicate adjective, not directly modifying the noun inside the noun phrase.

Structure:

• O prejuízo = subject
• foi = verb
• grande = adjective describing the subject

This is similar to English:

• The loss was big

So grande comes after the verb because it is part of was big, not part of big loss.

If you wanted the adjective directly with the noun, you would say:

• o grande prejuízo

But that is a different structure.

In the singular, grande stays the same for masculine and feminine nouns.

So:

• o prejuízo foi grande
• a perda foi grande

In the plural, it becomes:

• os prejuízos foram grandes
• as perdas foram grandes

So the adjective only changes here for number, not gender.

The accent mark on í shows where the stress falls.

So the stressed syllable is:

• pre-ju-Í-zo

Without the accent, a learner might stress it incorrectly.

It also helps show that the vowels are pronounced separately:

• ju-í rather than as one merged sound.

In European Portuguese, the pronunciation is approximately:

pruh-zhoo-EE-zoo

A few useful details:

• j sounds like the s in measure
• the stress is on í
• the final o in European Portuguese is often reduced, so it may sound closer to u
• the first unstressed vowel may also be reduced

You do not need a perfect imitation immediately, but the most important point is to stress -í-:

• pre-ju-Í-zo

No. Not in this structure.

O prejuízo foi is incomplete because ser needs something after it here — a noun, adjective, or phrase that says what the loss was like.

For example:

• O prejuízo foi grande.
• O prejuízo foi enorme.
• O prejuízo foi um problema sério.

So grande is necessary unless you replace it with something else.

Yes, absolutely.

That is a very natural way to make the statement stronger:

• O prejuízo foi grande. = The loss was big.
• O prejuízo foi muito grande. = The loss was very big.

Other common intensifiers are:

• bastante grande
• enorme
• muito grave depending on context

You would change the article, noun, verb, and adjective:

• Os prejuízos foram grandes.

Breakdown:

• o → os
• prejuízo → prejuízos
• foi → foram
• grande → grandes

This is a good example of agreement in Portuguese.

It is neutral and very natural, especially in business, legal, or news-related contexts.

It sounds normal in statements like:

• discussing a company’s results
• talking about damage after an accident
• describing financial consequences

It is not especially formal, but prejuízo is a more precise word than something very casual.