Luciam morae paenitet, quia sero ad convivium venit.

Because paenitet is used as an impersonal verb in Latin.

Instead of saying Lucia regrets the delay the way English does, Latin uses a structure more like:

• it causes Lucia regret for the delay

So with paenitet:

• the person who feels regret goes in the accusative
• the thing regretted often goes in the genitive

That is why we get:

• Luciam = Lucia as the person feeling regret
• morae = of the delay, the thing regretted

So Luciam morae paenitet literally works like it makes Lucia regret the delay.

With paenitet, the thing that someone regrets is commonly put in the genitive.

So:

• mora = delay
• morae = of the delay

This is just part of the standard construction of paenitet. A learner should remember it as:

• someone in the accusative
• something in the genitive
• paenitet

For example:

• me erroris paenitet = I regret the mistake
• eum culpae paenitet = he regrets the fault

So Luciam morae paenitet follows the same pattern.

Paenitet means it causes regret, it makes someone sorry, or more naturally in English, someone regrets.

But the important point is that Latin does not build the sentence the same way English does.

English says:

• Lucia regrets the delay

Latin says something closer to:

• The delay causes regret to Lucia
• or Lucia is sorry for the delay

So when you see paenitet, it is best to learn the whole pattern, not just the dictionary gloss regret.

A very useful formula is:

• accusative person + genitive thing + paenitet

Because venit can represent either:

• venit = he/she comes (present)
• vēnit = he/she came / has come (perfect)

In normal printed Latin, vowel lengths are often not marked, so both appear as venit.

You tell the difference from context. Here, the sentence is about regret over being late to the banquet, so a completed action makes the best sense:

• quia sero ad convivium venit = because she came late to the banquet

If the sentence meant because she comes late to the banquet, that would sound odd in this context.

Because sero is an adverb, meaning late.

Here it modifies the verb venit:

• sero venit = she came late

An adjective like sera would describe a noun, not the action itself. For example:

• hora sera = a late hour

But in this sentence, Latin wants the adverb, because it is telling us how she came.

Ad with the accusative usually expresses motion toward something.

So:

• ad convivium = to the banquet

Since venire means to come, using ad + accusative is very natural:

• ad urbem venit = he came to the city
• ad domum venit = he came to the house

So sero ad convivium venit means she came late to the banquet.

Quia means because and introduces a clause giving the reason.

So the structure is:

• Luciam morae paenitet = Lucia regrets the delay
• quia sero ad convivium venit = because she came late to the banquet

Together:

• Lucia regrets the delay because she came late to the banquet

So quia is simply connecting the main statement with the explanation.

Here morae is singular genitive, meaning of the delay.

That may look confusing at first, because morae could also be:

• nominative plural
• dative singular
• genitive singular

But in this sentence, only genitive singular fits the construction with paenitet.

So it means:

• morae = of the delay
• not delays

Yes, Latin often has other ways to express similar ideas, but this sentence uses a very standard idiomatic construction.

For example, instead of paenitet, Latin can sometimes express sorrow with adjectives or nouns, depending on style and meaning. But paenitet is a common and important verb pattern, and learners are expected to recognize it.

So even if the English translation is straightforward, the Latin grammar is worth learning as its own pattern:

• Luciam morae paenitet

This is one of those places where Latin idiom differs sharply from English.

The basic order here is:

• Luciam morae paenitet = main clause
• quia sero ad convivium venit = subordinate clause

Latin word order is fairly flexible because the endings show the grammar. So the sentence could be rearranged in various ways without changing the basic meaning, for example:

• Morae Luciam paenitet
• Quia sero ad convivium venit, Luciam morae paenitet

But the given order is perfectly natural. A learner should focus more on the case endings and the construction of paenitet than on trying to force English word order onto the Latin.

The most important thing to memorize is the construction of paenitet:

• person affected → accusative
• thing regretted → genitive
• paenitet → regrets / is sorry for

So you can model it as:

• me culpae paenitet = I regret the fault
• eos erroris paenitet = they regret the mistake
• Luciam morae paenitet = Lucia regrets the delay

That is the key lesson of the sentence.