Avia infantem in gremio leniter movet, dum mater cenam parat.

Because infantem is the direct object of movet.

The grandmother is the one doing the action, and the baby is the one being moved. In Latin, a direct object normally goes in the accusative case.

• nominative: infans = the baby as subject
• accusative: infantem = the baby as object

So:

• infans movet = the baby moves
• avia infantem movet = the grandmother moves the baby

Gremio is ablative singular.

It depends on the preposition in. With in, Latin often makes this distinction:

• in
  • ablative = in/on a place, showing location
• in
  • accusative = into/onto a place, showing motion toward

Here the baby is already in the lap, not moving into it, so Latin uses the ablative:

• in gremio = in the lap

The noun is gremium, gremii, so its ablative singular is gremio.

Because Latin often leaves out a possessive word when it is obvious from context.

Here, in gremio naturally means in her lap, that is, in the grandmother’s lap, because she is the one holding and gently moving the baby.

If Latin wanted to make it explicit, it could say something like:

• in gremio suo = in her own lap

But that would be more emphatic or more specific than necessary here.

Leniter is an adverb, and it tells you how the grandmother moves the baby.

So:

• movet = she moves
• leniter movet = she moves gently

It modifies the verb, not the noun.

A useful pattern: many Latin adjectives form adverbs ending in -ter or -iter. Here leniter is related to lenis, meaning gentle or mild.

Both are present active indicative, third person singular.

• movet = she moves / is moving
• parat = she prepares / is preparing

This tense is very common for simple description. In English, depending on context, you might translate it either as:

• moves / prepares
• is moving / is preparing

Latin’s present tense can cover both ideas.

Here dum means while.

It introduces a subordinate clause that describes an action happening at the same time as the main action:

• main clause: Avia infantem in gremio leniter movet
• dum clause: dum mater cenam parat

So the sense is that both actions are going on simultaneously.

With this meaning of dum, Latin commonly uses the indicative, as it does here.

Because cenam is the direct object of parat.

The mother is preparing dinner, so dinner is the thing affected by the action. That makes it accusative.

The noun is cena, cenae, so:

• nominative singular: cena
• accusative singular: cenam

Latin has much freer word order than English because the endings show each word’s grammatical job.

In English, word order is crucial:

• The grandmother moves the baby is different from
• The baby moves the grandmother

In Latin, the endings already tell you who is subject and who is object:

• avia = nominative, subject
• infantem = accusative, object

So Latin can arrange words more flexibly for rhythm, style, or emphasis.

This sentence is quite natural Latin. The verb movet comes late in the clause, which is very common, but not required.

Yes, but each belongs to its own clause.

• avia is the subject of movet
• mater is the subject of parat

So the sentence has two clauses:

1. Avia infantem in gremio leniter movet
2. dum mater cenam parat

Each clause has its own subject and verb.

In context, it probably suggests gently rocking or swaying the baby.

The basic meaning of moveo is simply move, but context often narrows the sense. Since the baby is in the lap and is being moved gently, an English speaker would naturally understand something like rocking.

So movet is a general verb, but the rest of the sentence gives it a more specific feel.

Yes. Mater is a third-declension noun, and its nominative singular does not end in -a, even though it refers to a female person.

That can surprise beginners, because many feminine nouns in Latin are first declension and end in -a, such as avia.

So:

• avia = first declension
• mater = third declension

Both are feminine, but they belong to different declensions and have different forms.

The comma helps separate the main clause from the subordinate clause.

In modern printed Latin, punctuation is used for readability, much as in English. The comma here signals that dum mater cenam parat is an added clause explaining when the main action happens.

It is helpful, but the grammar does not depend on the comma. Latin manuscripts in antiquity were much less consistent with punctuation than modern editions are.