Fibula aurea nitidior est quam fibula argentea.

Because they are adjectives agreeing with fibula.

In Latin, adjectives must agree with the nouns they describe in:

• gender
• number
• case

Here, fibula is:

• feminine
• singular
• nominative

So the adjectives must also be feminine singular nominative:

• fibula aurea = golden brooch
• fibula argentea = silver brooch

The dictionary forms would be:

• aureus, aurea, aureum = golden
• argenteus, argentea, argenteum = silvery, silver

So aurea and argentea are just the feminine forms chosen to match fibula.

They are both nominative singular.

The sentence compares one brooch with another:

• Fibula aurea = the golden brooch
• fibula argentea = the silver brooch

With quam after a comparative, Latin often puts the second thing compared in the same case as the first. Since the first brooch is nominative, the second one is nominative too:

• nitidior est quam fibula argentea

So this literally works like:

• The golden brooch is shinier than the silver brooch

Because Latin usually forms the comparative of an adjective with a special comparative ending.

The basic adjective is nitidus, nitida, nitidum, meaning shining, bright, or glossy. Its comparative is:

• nitidior (masculine/feminine)
• nitidius (neuter)

So nitidior means shinier, brighter, or more gleaming.

Latin generally prefers this one-word comparative form rather than using something like more shiny.

Because nitidior is agreeing with fibula, which is singular feminine.

Comparative adjectives have a slightly different pattern from regular first/second-declension adjectives:

• masculine/feminine nominative singular: -ior
• neuter nominative singular: -ius

So:

• nitidior = masculine or feminine singular
• nitidius = neuter singular
• nitidiora would be neuter plural, so it would not fit fibula

Since fibula is feminine singular, nitidior is the correct form.

The comparison is built with:

• a comparative adjective: nitidior = shinier
• the word quam = than

So the pattern is:

• X nitidior est quam Y
• X is shinier than Y

Here:

• Fibula aurea = X
• fibula argentea = Y

So:

• Fibula aurea nitidior est quam fibula argentea
• The golden brooch is shinier than the silver brooch

Yes, very often it could.

Since the noun is understood from the first half of the sentence, Latin could say:

• Fibula aurea nitidior est quam argentea.

That still means:

• The golden brooch is shinier than the silver one.

Latin often omits repeated nouns when the meaning is clear.

The full version with fibula repeated is perfectly correct; it may simply be clearer for a learner or used for emphasis.

Yes. Latin often uses the ablative of comparison instead of quam.

So another correct version would be:

• Fibula aurea nitidior est fibulā argenteā.

Here fibulā argenteā is in the ablative.

Both mean the same thing:

• The golden brooch is shinier than the silver brooch.

A learner should know both patterns:

• comparative + quam
• comparative + ablative

Est is the verb is, from sum.

The sentence needs a linking verb in English, and Latin often uses it too:

• Fibula aurea nitidior est...
• The golden brooch is shinier...

Latin sometimes omits forms of sum when they are easy to understand from context, especially in poetry or very compressed style. But in a normal sentence like this, including est is natural and expected.

So:

• with est = normal and clear
• without est = possible in some contexts, but not the basic textbook form here

Not especially. Latin word order is more flexible than English word order.

This sentence is:

• Fibula aurea nitidior est quam fibula argentea.

But Latin could also rearrange it, for example:

• Fibula aurea est nitidior quam fibula argentea.
• Nitidior est fibula aurea quam fibula argentea.

Because the endings show the grammar, the exact order does not have to match English.

That said, word order can still affect emphasis. The given order is straightforward and easy to understand.

The comparative form nitidior comes from the positive adjective:

• nitidus, nitida, nitidum

meaning something like:

• shining
• bright
• glossy
• polished

Its comparative is:

• nitidior, nitidius = shinier / brighter

So if you were looking it up, you would normally start with nitidus.

By itself, aurea can mean golden, and that may suggest either:

• actually made of gold, or
• having a golden appearance

Likewise, argentea can mean silver or silvery.

The exact nuance depends on context. In many simple learning sentences, it is natural to understand:

• fibula aurea = a gold brooch
• fibula argentea = a silver brooch

But grammatically the adjectives themselves are simply describing the brooches as golden and silver/silvery.

Latin has no definite article like English the.

So fibula can mean:

• a brooch
• the brooch

The context tells you which is more natural.

In this sentence, English usually translates with the:

• The golden brooch is shinier than the silver brooch

But Latin does not need a separate word for the.

Here is the basic breakdown:

• fibula: first declension noun
• aurea: first/second declension adjective, feminine form
• argentea: first/second declension adjective, feminine form
• nitidior: comparative adjective, declined like a third-declension comparative
• est: verb from sum
• quam: conjunction/adverb used in comparisons

This is useful because it shows that not all adjectives decline the same way:

• aurea and argentea follow the common first/second-declension adjective pattern
• nitidior follows the comparative pattern, which is different

In a sentence like this, yes:

• quam = than

But more generally, quam can appear in different kinds of expressions and does not always have exactly the same force in every context.

For beginners, the important thing here is:

• after a comparative adjective like nitidior, quam introduces the second thing being compared

So in this sentence, translating it as than is exactly right.