Parva avis in nido sedet.

Because parva has to agree with avis in gender, number, and case.

• avis = bird
• Here, avis is nominative singular
• avis is usually feminine

So the adjective parvus, parva, parvum (small) must also be feminine nominative singular, which is parva.

That is why Latin says parva avis = small bird.

Avis is in the nominative singular.

You can tell this mainly from its job in the sentence: it is the subject of sedet (sits / is sitting). The bird is the one doing the action.

So:

• avis = subject
• subjects are normally in the nominative
• therefore avis is nominative singular here

Also, the verb sedet is third person singular, so it matches a singular subject: the bird sits.

Classical Latin does not have articles like English a, an, and the.

So parva avis can mean:

• a small bird
• the small bird

The exact sense depends on the context. In an isolated sentence, English often translates it as a small bird.

Because in can take different cases depending on the meaning.

With in:

• in + ablative = in / on in the sense of location
• in + accusative = into / onto in the sense of motion toward

Here the bird is already in the nest, not moving into it. So Latin uses the ablative:

• nido = ablative singular of nidus
• in nido = in the nest

If the sentence meant The small bird goes into the nest, Latin would use in nidum.

Nido is the ablative singular of nidus, which means nest.

A quick breakdown:

• dictionary form: nidus
• stem: nid-
• ablative singular ending for a second-declension masculine noun: -o
• so: nido

Because it follows in with the meaning of location, the ablative is exactly what we expect.

Sedet is from the verb sedeo, sedere, meaning to sit or to be sitting.

Sedet is:

• present tense
• third person singular
• active voice

So it means:

• he/she/it sits
• or he/she/it is sitting

In this sentence, the subject is avis (bird), so sedet means the bird sits or the bird is sitting.

Yes. Latin’s present tense often covers both ideas.

So sedet can be translated as:

• sits
• is sitting

English sometimes makes a stronger distinction between simple present and progressive present, but Latin usually does not. The context tells you which English wording sounds best.

Latin word order is more flexible than English word order because the endings show how the words function.

So Parva avis in nido sedet is perfectly normal, but Latin could also say things like:

• Avis parva in nido sedet
• In nido parva avis sedet
• Sedet in nido parva avis

These all mean basically the same thing: A small bird sits in the nest.

However, word order can change the emphasis:

• putting in nido first may emphasize the location
• putting sedet first may emphasize the action
• keeping parva avis together is a very natural way to present the subject

In Latin, adjectives can come before or after the noun. Both are common.

So both of these are possible:

• parva avis
• avis parva

In this sentence, parva avis is just a natural, straightforward order. It groups the adjective and noun neatly together as small bird.

Unlike English, Latin does not rely on position alone to show the relationship, because the matching endings already tell you that parva modifies avis.

Because parva agrees with avis, not with nido.

Compare the forms:

• parva = feminine nominative singular
• avis = feminine nominative singular
• nido = masculine ablative singular

Since parva matches avis in gender, number, and case, it must describe avis.

If Latin wanted to say in the small nest, it would need a form that matches nido, such as in parvo nido.

They are:

• parvus, parva, parvum = small
• avis, avis = bird
• in = in, on, into, depending on case and context
• nidus, nidi = nest
• sedeo, sedere, sedi, sessum = sit

Latin dictionaries usually list nouns and verbs in standard forms, not necessarily the exact form you see in the sentence. So when learning, it is useful to connect the sentence forms back to their dictionary entries.