Learn Hardcore Croatian: Novi most je širi od starog mosta. - The new bridge is wider than the old bridge.

novi most – new bridge (correct: masculine)
nova most – would be new bridge with feminine agreement → wrong, because most is not feminine
novo most – would be neuter agreement → also wrong

You can see the pattern with other masculine nouns:

novi auto – new car (auto = m.)
novi grad – new city (grad = m.)

Why is širi used instead of something like više širok to mean wider?

Croatian usually forms comparatives by changing the adjective itself, not by adding a separate word like više (more) in front of it.

For širok (wide), the comparative is:

širok → širi – wide → wider

Other examples:

velik → veći (big → bigger)
dobar → bolji (good → better)
jeftin → jeftiniji (cheap → cheaper)

You can use više with some adjectives (especially longer or borrowed ones), for example:

više praktičan – more practical

But for common short adjectives like širok, the natural and correct form is the built‑in comparative širi, not više širok.

Why is širi in that exact form and not changed for case like starog or mosta?

Širi is a predicate adjective: it describes the subject most via the verb je (is).

Predicate adjectives in sentences like X je Y (The bridge is wide/wider) appear in the nominative, because they match the subject:

Novi most je širi. – The new bridge is wider.
- novi most – nominative (subject)
- širi – nominative (predicate adjective, agrees with the subject)

The comparison part od starog mosta does not change širi, because it’s not the subject; it’s just what you’re comparing to.

So:

subject side: nominative → novi most … širi
thing compared to: genitive → od starog mosta

Why is od used here, and how does it mean than?

The preposition od basically means:

from / of / since

But it has a special use in comparisons with comparative adjectives and adverbs:

Novi most je širi od starog mosta.
→ The new bridge is wider than the old (bridge).

Structurally, Croatian is saying: wider from the old bridge, but idiomatically this is just wider than the old bridge.

You’ll see the same pattern with other adjectives:

Viši je od mene. – He is taller than me.
Ovaj jeftiniji od onog. – This one is cheaper than that one.

In all of these, od governs the genitive case in the thing you compare to.

Why do we say od starog mosta and not od stari most?

Because od always takes the genitive case.

So after od, both the adjective and the noun must be in genitive singular masculine here:

adjective: star
- nominative: stari (old)
- genitive: starog
noun: most
- nominative: most (bridge)
- genitive: mosta

Therefore:

od starog mosta = from/of the old bridge → used as than the old bridge.

Od stari most would incorrectly use nominative, ignoring the genitive that od requires.

Why is it mosta and not mostu after od?

Both mosta and mostu are valid forms, but they are different cases:

mosta – genitive singular (of the bridge)
mostu – dative/locative singular (to the bridge / at the bridge / on the bridge, depending on preposition)

The preposition od always takes the genitive, so you must say:

od mosta – from the bridge / of the bridge / than the bridge

You would use mostu after prepositions that need dative/locative, for example:

k mostu – towards the bridge (dative)
na mostu – on the bridge (locative)

But never od mostu, because od does not go with dative/locative.

Why is there no word for “the” in Novi most je širi od starog mosta?

Croatian has no articles (no the/a/an). Definiteness (whether you mean a bridge or the bridge) is understood from context or word choice, not from a separate word.

So:

novi most can mean a new bridge or the new bridge, depending on the situation.
stari most / starog mosta can mean an old bridge or the old bridge.

In this particular context, if speakers are clearly talking about two specific bridges (a new one and an old one), it’s understood as:

The new bridge is wider than the old (bridge).

You don’t add anything like the to mark this; Croatian simply doesn’t use articles.

Why is je in the second position? Could I move it?

The verb je (is) is a clitic (an unstressed short word) and Croatian strongly prefers clitics in second position in the clause.

In Novi most je širi od starog mosta:

First element: Novi most (treated as one unit)
Second position: je
Rest of the sentence: širi od starog mosta

Other common placements that respect the second-position rule:

Novi je most širi od starog mosta. – Here Novi is first, je stays second.
Most je novi i širi od starog mosta.

Putting je at the very end (Novi most širi od starog mosta je) sounds very unnatural or wrong in standard Croatian.

Is Novi je most širi od starog mosta also correct, and does it change the meaning?

Yes, Novi je most širi od starog mosta is grammatically correct.

It still means: The new bridge is wider than the old (bridge).

The difference is mainly in emphasis and style:

Novi most je širi od starog mosta.
→ neutral, very common, straightforward.
Novi je most širi od starog mosta.
→ puts a bit more stress on novi (the new one), can sound more contrastive or stylistically marked, especially in spoken language.

Both respect the rule that je appears in second position in the clause.

Could I drop je and just say Novi most širi od starog mosta?

In normal, full sentences in standard Croatian, you need the verb je:

Novi most je širi od starog mosta. – correct full sentence.

Dropping je:

Novi most širi od starog mosta.
– This might appear in headlines, notes, or telegraphic style, but it is not a standard full sentence in regular speech or writing.

So in normal conversation or writing, you should keep je.

What is the basic form of starog and how is it declined with most?

The basic dictionary form is star (masculine singular), usually cited as stari in nominative with a noun.

For a masculine noun like most, singular forms often used are:

Nominative (subject):
- stari most – the old bridge
Genitive (of, from, than):
- starog mosta – of the old bridge / than the old bridge
Dative/Locative (to, at, on):
- starom mostu – to/on the old bridge
Accusative (direct object, motion towards):
- stari most – I see the old bridge
Instrumental (with):
- starim mostom – with/by the old bridge

In our sentence, after od, we must use the genitive: starog mosta.

Can I use nego instead of od here, and what’s the difference?

You can also compare using nego, especially when:

you are comparing two nominative elements, or
you continue with a whole clause.

For this specific sentence:

Novi most je širi od starog mosta.
– completely natural and standard.

You could say:

Novi most je širi nego stari most.
– grammatically OK, using nego + nominative (stari most).

Subtle differences:

od + genitive (od starog mosta) is the default and most neutral way to compare quantities or degrees (wider, higher, bigger, etc.).
nego + nominative (nego stari most) feels a bit more contrastive or “X rather than Y”-like, and is also common, especially when you compare whole phrases or clauses:
- Novi most je širi nego što misliš. – The new bridge is wider than you think.
- Bolje je čekati nego žuriti. – It’s better to wait than to hurry.

For your level, it’s perfectly fine (and often preferable) to stick with od + genitive:
Novi most je širi od starog mosta.