Produsul nu este numai defect, ci și deteriorat.

Romanian usually adds the definite article to the end of the noun instead of putting a separate word in front, as English does with the.

• produs = product
• produsul = the product

So Produsul means the product. This is one of the first big differences English speakers notice in Romanian: the article is often attached to the noun.

In Romanian, the negative particle nu normally comes directly before the verb.

So:

• este = is
• nu este = is not

That is the normal word order for negation. English uses is not; Romanian uses nu este.

You may also hear nu e in everyday speech, where e is a shorter form of este.

This is a very common Romanian structure meaning not only ... but also ...

So:

• nu numai defect = not only defective
• ci și deteriorat = but also damaged/deteriorated

Together:

• nu numai ..., ci și ... = not only ..., but also ...

It is used to add emphasis and show that the second description is an additional, often stronger, point.

Because Romanian normally uses ci after a negative first part when correcting or adding a contrasting second part.

In this sentence:

• nu numai defect sets up a negative-based contrast
• ci și deteriorat completes that contrast

So ci și is the natural pair with nu numai.

A good way to remember it is:

• nu numai ..., ci și ... = not only ..., but also ...

Using just și would sound incomplete or less idiomatic in this structure.

They are similar, but not identical.

• defect usually means faulty, defective, or having a flaw, often from manufacture or function
• deteriorat usually means damaged, worn, or made worse through use, time, or conditions

So the sentence suggests two separate problems:

1. the product has a defect
2. it is also physically or materially damaged

That is why both adjectives appear together: they are related, but they are not exact synonyms.

Because they describe produsul, which is masculine singular.

In Romanian, adjectives usually agree with the noun in gender and number.

Here:

• produsul = masculine singular
• defect = masculine singular
• deteriorat = masculine singular

If the noun were feminine singular, the forms would usually change:

• marfa = the merchandise/goods
• Marfa nu este numai defectă, ci și deteriorată.

So adjective agreement is important in Romanian.

Yes. That is completely natural in everyday Romanian.

• este is the full form
• e is the shorter, very common spoken form

So these are both correct:

• Produsul nu este numai defect, ci și deteriorat.
• Produsul nu e numai defect, ci și deteriorat.

The version with este may sound a little more careful or formal, while e is very common in speech.

Yes, doar can often replace numai.

So you may also hear:

• Produsul nu este doar defect, ci și deteriorat.

Both numai and doar can mean only. In this structure, both are possible and natural.
However, nu numai ..., ci și ... is a very fixed and familiar pattern, so learners will see it often.

In Romanian, și often covers the meaning of also in this structure.

So:

• ci și deteriorat literally looks like but also damaged
• but Romanian does not need a separate extra word beyond și here

The pair ci și already gives the full idea of but also.

A helpful approximate pronunciation for an English speaker is:

pro-DOO-sul noo ES-teh nu-MAI de-FEKT, chee shuh de-te-ree-o-RAT

A few pronunciation notes:

• u is usually like oo in food
• ci here sounds like chee
• și sounds like shy said very quickly, or roughly shuh/shee depending on accent and speed
• defect is stressed on the second syllable: de-FEKT
• deteriorat is stressed near the end: de-te-ree-o-RAT

Romanian spelling is generally quite regular, so pronunciation becomes easier with practice.

Some small changes are possible, but this version is the standard and most natural one.

The basic structure is:

• [noun] + nu este numai + adjective + ci și + adjective

So:

• Produsul nu este numai defect, ci și deteriorat.

That is the clearest form for learners and the one you should use first. Romanian does allow some flexibility for emphasis, but changing the order too much can sound unnatural or advanced. For now, it is best to learn nu numai ..., ci și ... as a fixed pattern.

It is neutral to slightly formal.

Why?

• produsul is standard vocabulary
• defect and deteriorat are common in product descriptions, complaints, reports, and customer service
• nu este numai ..., ci și ... is a polished, standard structure

So this sentence would sound perfectly natural in:

• a complaint email
• a product review
• a customer service message
• a formal or neutral conversation

In very casual speech, someone might choose shorter wording, but this sentence is completely normal and correct.