Learn Hardcore Croatian: Ove knjige su dobre.

Singular:
- ovaj – this (masculine)
- ova – this (feminine)
- ovo – this (neuter)
Plural:
- ovi – these (masculine)
- ove – these (feminine)
- ova – these (neuter)

Since knjige (books) is a feminine plural noun, you must use the feminine plural demonstrative ove:
ove knjige = these books.

ova knjiga would be this book (singular, feminine).
ovi ljudi would be these people (masculine plural).

Why is knjige plural and not knjiga?

Knjiga is a feminine noun meaning book.

knjiga = book (singular, nominative)
knjige = books (plural, nominative)

In Ove knjige su dobre, we are talking about more than one book, so the noun must be plural: knjige.

Very roughly:

Ova knjiga je dobra. = This book is good. (singular)
Ove knjige su dobre. = These books are good. (plural)

What form of to be is su, and why do we use it here?

Su is the 3rd person plural present tense of biti (to be).

Present tense of biti:

ja sam – I am
ti si – you are (singular, informal)
on/ona/ono je – he/she/it is
mi smo – we are
vi ste – you are (plural or formal)
oni/one/ona su – they are

The subject here is ove knjige (these books), which is third person plural, so we use su:
Ove knjige su dobre. = These books are good.

You may also see jesu, which is an emphatic version used mainly to stress or contrast:

Jesu dobre, ali su skupe. = They are good, but they are expensive.

Why is the adjective dobre and not dobar, dobri, or dobro?

Adjectives in Croatian agree in gender, number, and case with the noun they describe.

The base adjective here is dobar (good). In the nominative:

Singular:
- masculine: dobar – good
- feminine: dobra – good
- neuter: dobro – good
Plural:
- masculine: dobri – good
- feminine: dobre – good
- neuter: dobra – good

Since knjige is feminine plural nominative, the adjective must also be feminine plural nominative: dobre.

So:

Ova knjiga je dobra. – This book is good. (feminine singular)
Ove knjige su dobre. – These books are good. (feminine plural)
Ovi filmovi su dobri. – These movies are good. (masculine plural)
Ova vina su dobra. – These wines are good. (neuter plural)

Is the word order fixed, or can I move the words around?

Croatian word order is more flexible than English. Ove knjige su dobre is the most neutral, straightforward order.

You may also hear:

Ove knjige dobre su. – sounds a bit marked/emphatic.
Knjige su dobre. – The books are good.
Dobre su ove knjige. – These books are good (with more emphasis on good or on these books in contrast to others).
Ove su knjige dobre. – Also possible; often adds slight emphasis on ove.

The meaning stays essentially the same; changes mostly affect emphasis and focus, not the basic grammar.

Do I always have to use ove? Can I just say Knjige su dobre?

You do not always have to use a demonstrative like ove.

Knjige su dobre. = The books are good or Books are good (context decides which).
This just refers to books that are already understood from context or in general.
Ove knjige su dobre. = These books are good.
Here you are pointing out specific books (for example, the ones you are holding or standing next to).

Croatian has no articles like the or a, so adding a demonstrative (ove, te, one) is often how you make something specific, like English these or those.

What is the difference between ove knjige, te knjige, and one knjige?

Croatian uses three basic demonstratives based on distance (physical or mental):

ove knjige – these books
- usually near the speaker (or associated with the speaker)
te knjige – those books
- usually near the listener, or somewhat further away from the speaker
one knjige – those books (over there)
- usually far from both speaker and listener, or more distant in context

So:

Ove knjige su dobre. – These books (here, near me) are good.
Te knjige su dobre. – Those books (near you / not with me) are good.
One knjige su dobre. – Those books there (further away) are good.

Which case is ove knjige in, and does that form ever change?

In Ove knjige su dobre, ove knjige is in the nominative plural because it is the subject of the sentence.

For feminine plural, ove knjige looks the same in nominative and accusative:

Nominative (subject):
- Ove knjige su dobre. – These books are good.
Accusative (direct object):
- Vidim ove knjige. – I see these books.

Other cases will change:

Genitive: ovih knjiga – of these books
Dative/Locative: ovim knjigama – to/at these books
Instrumental: ovim knjigama – with these books

So the exact form ove knjige is nominative or accusative plural feminine; you know which from the sentence role.

Does Croatian use articles like the or a in this sentence?

No. Croatian does not have articles like English the or a/an.

knjiga by itself can mean a book or the book, depending on context.
knjige can mean books or the books.

To make something explicitly specific, Croatian often uses demonstratives (ova, ove, taj, onaj, etc.):

Ove knjige su dobre. – These books are good.
Knjige su dobre. – The books are good / Books are good (context decides).

How do I make this sentence negative?

To negate biti (to be) in the present, you use nisam, nisi, nije, nismo, niste, nisu.

So:

Ove knjige su dobre. – These books are good.
Ove knjige nisu dobre. – These books are not good.

Full negative paradigm of biti:

ja nisam – I am not
ti nisi – you are not
on/ona/ono nije – he/she/it is not
mi nismo – we are not
vi niste – you are not
oni/one/ona nisu – they are not

How do you pronounce Ove knjige su dobre?

Approximate pronunciation (IPA):

Ove – /ɔʋe/
- o as in or (shorter), v is like English v, but often pronounced a bit like w between vowels.
knjige – /kɲiɡe/
- k as in key
- nj is a single sound, /ɲ/, like ñ in Spanish señor or ny in English canyon
- i as in machine
- g always hard, as in go
- e as in met
su – /su/
- s as in see, u as in boot
dobre – /dɔbre/
- d as in dog
- o as in or (shorter)
- e as in met

Spoken smoothly: O-ve kɲi-ge su do-bre.
Stress is usually on the first syllable of each word: Òve knjìge su dòbre (rough pattern).

How would I say This book is good versus These books are good?

Using the same words, but with singular forms:

This book is good.
Ova knjiga je dobra.
- ova – this (feminine singular)
- knjiga – book (feminine singular)
- je – is (3rd person singular of biti)
- dobra – good (feminine singular)
These books are good.
Ove knjige su dobre.
- ove – these (feminine plural)
- knjige – books (feminine plural)
- su – are (3rd person plural)
- dobre – good (feminine plural)

Notice how all parts (demonstrative, noun, verb, adjective) change to match singular vs. plural.

Can you summarize the agreement in this sentence?

Yes. In Ove knjige su dobre we have:

ove – demonstrative, feminine plural nominative
knjige – noun, feminine plural nominative
dobre – adjective, feminine plural nominative
su – verb in 3rd person plural present

So:

Gender: all agreeing as feminine
Number: all agreeing as plural
Case: the noun phrase ove knjige and the predicate adjective dobre are both in nominative, because they are subject + subject complement.

This kind of full agreement is very typical for Croatian sentences with to be and a describing adjective.