Zategni vijak odvijačem.

Zategni is the singular informal imperative of the verb zategnuti. It is the form you use when telling one person to do something: Tighten ...

The base verb zategnuti is perfective, so the command suggests completing the action: tighten it up / make it tight.

A few related forms:

• zategnuti = to tighten (perfective)
• zatezati = to tighten, be tightening (imperfective)
• zategni! = tighten! (to one person)
• zategnite! = tighten! (to more than one person, or politely to one person)

In Serbian, the subject is often omitted when it is already clear from the verb form. The imperative zategni already tells you that the command is aimed at you (singular, informal).

So:

• Zategni vijak odvijačem. = Tighten the screw with a screwdriver.
• Adding ti would usually be unnecessary.

This is very normal in Serbian.

Vijak is the direct object, so it is in the accusative case.

However, for many masculine inanimate nouns, the accusative singular is the same as the nominative singular. That is why it still looks like vijak.

So:

• nominative: vijak
• accusative: vijak

If it were a masculine animate noun, the accusative would usually look different.

Because it is in the instrumental singular.

The instrumental case is often used to show the tool, means, or instrument used to perform an action. In this sentence, the tool is the screwdriver.

So:

• odvijač = screwdriver
• odvijačem = with a screwdriver / using a screwdriver

This is one of the most common uses of the instrumental case in Serbian.

Because Serbian often uses the instrumental case without a preposition to express the means or tool used for an action.

So:

• odvijačem = with a screwdriver / using a screwdriver

This is more natural here than adding a preposition.

Compare:

• Pišem olovkom. = I am writing with a pencil.
• Sečem nožem. = I am cutting with a knife.
• Zategni vijak odvijačem. = Tighten the screw with a screwdriver.

Usually, in this sentence, bare instrumental is the normal choice: odvijačem.

Using sa odvijačem is not the usual way to express using a tool here. Sa more naturally means with in the sense of accompanied by or together with, not simply by means of.

So for tools:

• more natural: odvijačem
• less natural here: sa odvijačem

A learner should generally remember:

• tool/means → often instrumental without a preposition

This is mainly a question of aspect.

• zategni comes from the perfective verb zategnuti
  • it suggests a completed result
  • tighten it
• zateži comes from the imperfective verb zatezati
  • it suggests an ongoing or repeated action
  • keep tightening / be tightening

So in a practical instruction, zategni vijak sounds like:

• tighten the screw properly
• bring it to the finished state

While zateži vijak could sound more like:

• keep tightening the screw
• continue the action

Yes. Serbian word order is fairly flexible, because case endings help show what each word is doing.

The most neutral order here is:

• Zategni vijak odvijačem.

But other orders are possible for emphasis, for example:

• Vijak zategni odvijačem. = puts more focus on the screw
• Odvijačem zategni vijak. = puts more focus on the tool

Even though the order can change, not every version sounds equally natural in every context. The original sentence is the most straightforward instruction.

Often yes, but not always perfectly. Vijak can correspond to screw and sometimes bolt, depending on context and technical usage.

In everyday learning materials, vijak is often easiest to remember as:

• screw

But in real-life hardware vocabulary, Serbian terms can overlap differently from English. So the exact translation may depend on the object being discussed.

A rough English-friendly guide:

• Zategni ≈ za-TEG-nee
• vijak ≈ VEE-yak
• odvijačem ≈ od-vee-YA-chem

A few useful pronunciation notes:

• j is pronounced like English y in yes
• č sounds like ch in church
• Serbian pronunciation is generally quite regular, so words are usually pronounced close to how they are written

You would change the imperative verb from zategni to zategnite.

So:

• Zategni vijak odvijačem. = to one person, informal
• Zategnite vijak odvijačem. = to several people, or politely to one person

The rest of the sentence stays the same.