Mater atrium ornat, ut convivae laeti sint.

Mater is in the nominative singular, which is the case normally used for the subject of a sentence.

• mater = mother
• It is a third-declension noun
• Its nominative singular form is simply mater

So in Mater atrium ornat, mater is the one doing the action: she decorates.

Atrium is the direct object of ornat, so it is in the accusative singular.

• atrium is a second-declension neuter noun
• Nominative singular: atrium
• Accusative singular: atrium

Because neuter second-declension nouns often have the same form in the nominative and accusative singular, the form does not change here. Its role is understood from the verb and sentence structure: it is the thing being decorated.

Here ut introduces a purpose clause. In this sentence it means:

• so that
• in order that

So Mater atrium ornat, ut convivae laeti sint means that the mother decorates the atrium for the purpose of making the guests happy.

This is a very common Latin construction:

• main clause
• ut
  • subjunctive verb

Because after ut in a purpose clause, Latin normally uses the subjunctive, not the indicative.

• sunt = they are in the indicative
• sint = they may be / might be / be in the present subjunctive

So ut convivae laeti sint literally means something like:

• so that the guests may be happy
• in order that the guests be happy

In smoother English, we often just say so that the guests are happy, but Latin expresses the idea of purpose through the subjunctive.

Sint is the present subjunctive active, third person plural, of sum, esse.

Its basic breakdown is:

• verb: sum, esse = to be
• tense: present
• mood: subjunctive
• person/number: third plural

It matches convivae, which is plural, so the verb must also be plural: the guests may be / are to be happy.

The form convivae can potentially be more than one thing, which is exactly why learners often ask about it.

Here it is nominative plural, meaning guests.

We know this because:

• it goes with laeti, which is also nominative plural
• it goes with sint, which is third person plural
• it is the subject of the ut clause

So in this sentence:

• convivae = the guests
• laeti = happy
• sint = may be / are

Together: the guests may be happy

Laeti is an adjective meaning happy, and it agrees with convivae.

Since convivae is:

• nominative
• plural

the adjective must also be:

• nominative
• plural

So we get laeti.

Also, laeti is the masculine plural form. That usually means the guests are understood as:

• male, or
• a mixed group

If the guests were specifically female, Latin would normally use laetae instead.

Because laeti is a predicate adjective, not an object.

With forms of to be such as sum, Latin uses the nominative for both:

• the subject
• the adjective describing the subject

So:

• convivae = nominative plural
• laeti = nominative plural
• sint = may be

This is just like saying the guests are happy. Happy describes the subject, so it agrees with it.

Ornat is:

• present tense
• indicative mood
• active voice
• third person singular

It comes from orno, ornare, meaning to decorate or to adorn.

So ornat means:

• she decorates
• is decorating, depending on context

Since the subject is mater, third person singular is exactly what we expect.

Because the two clauses do different jobs.

Main clause

Mater atrium ornat

This states a fact or action, so Latin uses the indicative:

• ornat

Purpose clause

ut convivae laeti sint

This expresses the goal or intended result of the action, so Latin uses the subjunctive:

• sint

That contrast is very typical in Latin:

• indicative for the main statement
• subjunctive for a purpose clause introduced by ut

Correct. Latin has no articles like English the or a/an.

So:

• mater can mean mother, a mother, or the mother
• atrium can mean atrium, an atrium, or the atrium
• convivae can mean guests or the guests

Which English article to use depends on context. In a teaching sentence like this, English often supplies the where it sounds natural.

Latin word order is more flexible than English word order because the endings show each word’s function.

This sentence has a clear and fairly straightforward order:

• Mater = subject
• atrium = object
• ornat = verb
• ut convivae laeti sint = purpose clause

But Latin could rearrange parts of the sentence for emphasis without changing the basic meaning, for example:

• Atrium mater ornat, ut convivae laeti sint
• Ut convivae laeti sint, mater atrium ornat

The endings still tell you what each word is doing.

Yes. Ut is a very common Latin word with several uses, so learners often need to identify it from context.

Some common meanings are:

• so that / in order that with the subjunctive for purpose
• that with the subjunctive in some result clauses
• as or when in some contexts

In this sentence, because the main idea is that the mother decorates the atrium for a purpose, and because the verb is subjunctive (sint), ut is best understood as introducing a purpose clause: so that or in order that.