Opišite postignuće.

Opišite is the imperative form, so it is giving an instruction or request: Describe ...

More specifically, it is the 2nd person plural imperative of opisati (to describe).

In Croatian, this form is used:

• when speaking to more than one person
• or when speaking politely/formally to one person

So Opišite postignuće. can mean:

• Describe the achievement. said to several people
• Describe the achievement. said politely to one person

Opisati is the infinitive, meaning to describe.

Croatian uses the infinitive as the dictionary form, but in a sentence like this you need a conjugated verb form. Since this sentence is a command/request, Croatian uses the imperative:

• opisati = to describe
• opišite = describe!

So Opišite postignuće. is the natural way to say Describe the achievement.

Here postignuće is in the accusative case because it is the direct object of the verb Opišite.

You are describing what?
→ postignuće

The noun postignuće is neuter singular, and for many neuter nouns in Croatian, the nominative and accusative singular look the same.

So:

• nominative: postignuće = an achievement
• accusative: postignuće = an achievement / the achievement as the object

That is why the form does not change here.

Postignuće means achievement or accomplishment.

It usually refers to something that has been successfully done or attained, for example:

• an academic achievement
• a professional accomplishment
• a personal success

Its dictionary form is already postignuće.

Useful related forms:

• singular: postignuće
• plural: postignuća

Yes, it can be.

In Croatian, the 2nd person plural form is also used as a formal/polite singular form, similar to how some languages use a plural form for politeness.

So:

• Opiši postignuće. = informal, to one person
• Opišite postignuće. = formal to one person, or neutral to multiple people

If you see Opišite in instructions, forms, exams, or official contexts, that formal tone is very common.

Opisati is a perfective verb, while opisivati is its imperfective partner.

In this sentence, Opišite sounds natural because it asks for a complete description of the achievement as a finished task.

Very roughly:

• opisati = to describe completely / as a completed action
• opisivati = to be describing, to describe repeatedly, or to describe in an ongoing/general way

In instructions and prompts, Croatian often prefers the perfective imperative when asking someone to complete a specific task:

• Opišite postignuće. = Describe the achievement.

A helpful approximate pronunciation is:

oh-PEE-shee-teh poh-steeg-NOO-cheh

A few letter notes:

• š sounds like sh in ship
• ć is a soft sound, somewhat like a softer ch
• č and ć are different in Croatian, but learners often need time to hear and produce the difference clearly

So:

• Opišite ≈ oh-PEE-shee-teh
• postignuće ≈ poh-steeg-NOO-cheh

Yes, Croatian word order is more flexible than English word order.

The neutral, most natural order here is:

• Opišite postignuće.

That said, Croatian can move words for emphasis. For example, Postignuće opišite. is possible, but it sounds more marked or emphatic.

For a learner, the best version to use is the standard one:

• Opišite postignuće.

Yes. Croatian often does not use articles like English a and the, because Croatian has no articles.

So postignuće by itself can mean:

• an achievement
• the achievement

The exact meaning depends on context.

For example:

• on a general worksheet prompt, it may feel like Describe an achievement
• in a specific discussion about one known achievement, it may mean Describe the achievement

You would usually say:

• Opiši postignuće.

Here Opiši is the 2nd person singular imperative, used with someone you address informally.

Compare:

• Opiši postignuće. = informal singular
• Opišite postignuće. = formal singular or plural

This is a very common distinction in Croatian, so it is worth learning early.