Așteaptă o secundă.

Așteaptă here means wait!

In this sentence, it is the imperative form of the verb a aștepta = to wait.

So:

• a aștepta = to wait
• așteaptă! = wait!

In context, Așteaptă o secundă. means Wait a second.

Also, this form is used for singular informal commands, so you would say it to one person you address as you in a casual way.

It is informal singular.

Romanian, like many European languages, distinguishes between:

• informal singular = speaking to one person casually
• formal or plural = speaking politely to one person or to multiple people

So Așteaptă o secundă. is what you would say to:

• a friend
• a family member
• someone your age in a casual situation
• one person you are speaking to informally

If you want the formal/plural version, you would usually say:

• Așteptați o secundă. = Wait a second.

Because secundă is a feminine noun.

In Romanian:

• un is used with many masculine and neuter singular nouns
• o is used with feminine singular nouns

So:

• o secundă = a second
• o zi = a day
• o carte = a book

That means:

• secundă = second
• o secundă = a second / one second

Not always. Just like English wait a second, Romanian așteaptă o secundă is often used idiomatically to mean:

• wait a moment
• hold on
• just a second

So although it literally contains a second, speakers often use it more loosely, not to mean a precise unit of time.

Because Romanian often omits the subject pronoun when it is already clear from the verb form.

In English, you usually need:

• Wait a second.

Even though English also omits you in commands, in Romanian this happens very naturally because the verb ending already helps show who is being addressed.

Here, așteaptă already signals a command to one person, informal, so there is no need to add tu.

You could add tu for emphasis in some contexts, but normally you would just say:

• Așteaptă o secundă.

A rough English-friendly pronunciation is:

• uh-SHTEAP-tuh

A few details:

• ă is a short central vowel, similar to the a in sofa for many English speakers
• ș is pronounced like sh
• ea in așteaptă sounds like a diphthong, roughly eah

So the whole sentence is approximately:

• uh-SHTEAP-tuh o se-KOON-duh

This is only approximate, but it helps as a starting point.

Romanian uses diacritics, and they matter.

In this sentence you see:

• ș = pronounced sh
• ă = a distinct vowel sound, often like a reduced uh

So:

• așteaptă is not the same spelling as asteapta
• secundă is not the same as secunda

In normal Romanian writing, you should try to include these marks, because they are part of correct spelling.

The main stress is usually:

• aȘTEAPtă
• seCUNdă

So:

• aȘTEAPtă o seCUNdă

In natural speech, the most important word may get extra emphasis depending on context. For example:

• AȘTEAPTĂ o secundă. if you are insisting someone should wait
• Așteaptă O secundă. if you mean specifically one second

But the normal dictionary stress is:

• aȘTEAPtă
• seCUNdă

Yes, very often.

Stai o secundă literally uses stai from a sta = to stay / to stand / to remain, but in everyday Romanian it can also mean something like:

• wait a second
• hold on

So both are common:

• Așteaptă o secundă.
• Stai o secundă.

A small difference in feel:

• așteaptă is more directly tied to wait
• stai can sound a little more conversational in some contexts

Both are useful and natural.

No. Romanian has several natural alternatives, depending on tone and context.

Common ones include:

• Așteaptă un moment. = Wait a moment.
• Așteaptă puțin. = Wait a little / Wait a bit.
• Stai puțin. = Wait a bit / Hold on.
• Doar o clipă. = Just a moment.

So Așteaptă o secundă. is correct and common, but not the only way to express the idea.

The dictionary form is secundă.

In this sentence it means second, as a unit of time.

Related forms:

• o secundă = a second
• două secunde = two seconds
• secunda can also appear as the second in certain contexts, because Romanian adds the definite article to the end of the noun

For example:

• o secundă = a second
• secunda = the second

So in your sentence, o secundă is simply the indefinite form: a second.