Lucrul este important.

Because Romanian usually adds the definite article to the end of the noun.

• lucru = a thing / a work / work (indefinite, depending on context)
• lucrul = the thing / the work

So -l / -ul here is the equivalent of English the.

This is a very common Romanian feature:

• băiat = boy
• băiatul = the boy
• carte = book
• cartea = the book

So in Lucrul este important, lucrul is the definite form.

It depends on context. Lucru is a broad word and can mean:

• thing
• matter
• work
• sometimes task or issue

So lucrul could mean:

• the thing
• the matter
• the work

Even if the translation has already been given, it is useful to know that Romanian lucru is flexible and may not always match just one English word.

Yes. Este is a form of the verb a fi = to be.

In this sentence:

• lucrul = subject
• este = is
• important = adjective

So the structure is very similar to English:

• The thing is important.

You may also hear e instead of este in everyday speech:

• Lucrul e important.

Both are correct. Este is a little fuller and slightly more formal or careful in style.

Because the adjective must agree with the noun in gender and number, and here the noun is singular masculine/neuter.

Lucru is a neuter noun in Romanian. Neuter nouns behave:

• like masculine in the singular
• like feminine in the plural

Since lucrul is singular, the adjective takes the masculine singular form:

• important = masculine/neuter singular
• importantă = feminine singular
• importanți = masculine plural
• importante = feminine/neuter plural

Examples:

• Lucrul este important. = singular neuter noun, so important
• Cartea este importantă. = feminine singular
• Lucrurile sunt importante. = plural neuter, so feminine plural adjective

It is neuter.

Romanian neuter nouns are a bit special:

• in the singular, they act like masculine nouns
• in the plural, they act like feminine nouns

So:

• singular: un lucru important
• plural: două lucruri importante

That is why in your sentence the adjective is important, not importantă.

It could, but that word order is less neutral and sounds more marked or stylistic.

The normal, straightforward order is:

• Lucrul este important.

If you move important to the front:

• Important este lucrul

that puts extra emphasis on important, and it may sound literary, contrastive, or unnatural in ordinary conversation unless the context supports it.

For a learner, the safest pattern is:

• subject + este + adjective

No, not in a normal present-tense sentence like this.

Romanian usually keeps the verb:

• Lucrul este important.
• Lucrul e important.

You would not normally say:

• Lucrul important.

That would not work as a complete sentence in standard Romanian. It would sound more like a noun phrase, such as the important thing, not the thing is important.

A simple learner-friendly pronunciation guide would be:

• Lucrul ≈ LOO-krool
• este ≈ YES-te
• important ≈ im-por-TANT

A few notes:

• u is usually like oo in food
• e in este is like ye at the start: YES-te
• the r is trilled or tapped
• the final t in important is pronounced

Romanian spelling is fairly phonetic, so once you learn the sound rules, pronunciation becomes much easier than in English.

The plural would be:

• Lucrurile sunt importante.

Breakdown:

• lucrul = the thing / the work
• lucrurile = the things / the works
• este = is
• sunt = are
• important = singular adjective form
• importante = plural form used with neuter plural nouns

This is a very useful example of how Romanian neuter works:

• singular: lucrul este important
• plural: lucrurile sunt importante

Because Romanian does not need a dummy subject like English it in this kind of sentence.

English often uses it in sentences such as:

• It is important.

But here Romanian names the subject directly:

• Lucrul este important.

If the subject is already stated, there is no need for an extra pronoun.

Also, Romanian often omits subject pronouns when the verb already shows the person:

• Sunt aici. = I am here.

In your sentence, the subject is the noun lucrul, so no pronoun is needed anyway.

It is grammatically correct and understandable, but whether it feels natural depends on context.

Lucrul is a valid word, but in real-life Romanian people often choose more specific words, such as:

• munca = the work
• treaba = the task / the job / the matter
• lucrul acesta = this thing / this matter

So while Lucrul este important is fine for learning structure, in actual conversation a Romanian speaker might more naturally say:

• Lucrul acesta este important.
• Treaba asta este importantă.
• Munca este importantă.

It depends on what exactly thing/work refers to.

Yes, but the meaning changes.

• Lucrul este important. = The thing / the work is important.
• Un lucru este important. = One thing is important / A thing is important.

Un lucru este important is very common when introducing a point:

• Un lucru este important: trebuie să fim atenți. = One thing is important: we must be careful.

So both are correct, but lucrul is definite, while un lucru is indefinite.

Because here important is part of the predicate, not directly attached to the noun inside a noun phrase.

Compare:

1. Lucrul este important.

   • important describes the subject through the verb este
   • this means The thing is important

2. Lucrul important

   • this is a noun phrase
   • it means the important thing

So:

• este important = predicate adjective
• lucrul important = noun + adjective phrase

That distinction is important in Romanian, just as it is in English.