Copilul nu minte.

Romanian usually puts the definite article at the end of the noun, not as a separate word before it.

• copil = child / a child
• copilul = the child

So -ul is the masculine/neuter singular definite article here.

This is one of the first big differences English speakers notice in Romanian:

• băiat = a boy
• băiatul = the boy
• om = a person / man
• omul = the person / the man

So Copilul nu minte. literally has the built into copilul.

Nu is the normal Romanian word for not.

In Romanian, standard negation usually works like this:

• subject + nu + verb

So:

• Copilul minte. = The child lies / is lying.
• Copilul nu minte. = The child does not lie / is not lying.

English uses do not or is not, but Romanian usually just puts nu directly before the verb.

Minte is the 3rd person singular present tense of the verb a minți, which means to lie in the sense of to tell something false.

So:

• eu mint = I lie
• tu minți = you lie
• el/ea minte = he/she lies
• copilul minte = the child lies

Because copilul is singular, the verb is singular too: minte.

English often says is lying, but Romanian can use the simple present where English uses either:

• lies
• is lying

So Copilul nu minte. can mean:

• The child does not lie
• The child is not lying

The exact meaning depends on context.

Romanian does have ways to make the action feel more specifically ongoing, but in everyday language the simple present is very often enough.

It can mean either one, depending on context.

Romanian present tense often covers both:

• a general truth / habit
• a current action

So this sentence could mean:

• The child does not lie = the child is generally honest
• The child is not lying = right now, the child is telling the truth

If you only see the sentence by itself, both readings are possible.

Romanian often does not need subject pronouns because the verb ending already gives information about the person and number.

Here, minte tells you it is 3rd person singular:

• he lies
• she lies
• it lies
• or a singular noun such as the child lies

Since the subject is already named as copilul, adding a pronoun would be unnecessary.

Romanian uses subject pronouns mostly for:

• emphasis
• contrast
• clarity when needed

So Copilul nu minte. is completely natural.

This is the most neutral and basic order:

• Copilul nu minte.

Romanian word order is somewhat flexible, so other orders are possible for emphasis, but they are not the default for a beginner.

For example:

• Nu minte copilul. can be used, but it sounds more marked and may emphasize the denial.
• Copilul minte. / Copilul nu minte. are the standard straightforward patterns.

So as a learner, it is best to treat subject + nu + verb as the normal order here.

Yes, minte can also be a noun meaning mind.

For example:

• Are o minte bună. = He/She has a good mind.

But in Copilul nu minte., it is clearly the verb, because:

• it follows nu, which normally negates a verb
• the sentence structure is that of subject + negation + verb

So in this sentence, a Romanian speaker understands minte as lies / is lying, not mind.

A simple learner-friendly pronunciation guide would be:

• Copilul ≈ ko-PEE-lul
• nu ≈ noo
• minte ≈ MEEN-te

A few helpful notes:

• Romanian u is usually like oo in food
• Romanian i here sounds like ee in see
• Romanian e is like e in met
• the stress is usually:
  • coPILul
  • MINte

So the whole sentence sounds roughly like:

ko-PEE-lul noo MEEN-te

The difference is about definiteness:

• copil = a child / child
• copilul = the child

So compare:

• Un copil nu minte. = A child does not lie / A child is not lying
• Copilul nu minte. = The child does not lie / The child is not lying

In your sentence, copilul points to a specific child, not just any child in general.