Naulum et fenus magna sunt.

Because naulum et fenus is a compound subject: naulum and fenus.

Even though each noun is singular by itself, together they make a plural idea, so Latin uses a plural verb:

• naulum = singular
• fenus = singular
• naulum et fenus = two things, so plural

That is why the sentence has sunt = are, not est = is.

For the same reason: the adjective is describing both nouns together, not just one of them.

Since naulum et fenus forms a plural subject, the predicate adjective must also be plural. And because both nouns are neuter, the adjective must be neuter plural:

• masculine plural: magni
• feminine plural: magnae
• neuter plural: magna

So magna sunt means are great/large/important with a neuter plural adjective.

They are in the nominative case, because they are the subject of the sentence.

The basic structure is:

• naulum et fenus = the subject
• magna = predicate adjective
• sunt = verb

So the sentence is built as [subject] + [description] + [verb].

Because agreement in Latin is based on gender, number, and case, not on declension.

Here:

• naulum is neuter singular nominative
• fenus is neuter singular nominative

Together they form a neuter plural nominative idea, so the adjective becomes magna.

It does not matter that the nouns belong to different declensions. What matters is that together they are treated as plural neuter.

It is a predicate adjective.

A predicate adjective is an adjective linked to the subject by a form of to be. In English, this is like:

• The ships are large
• The costs are great

In Latin:

• Naulum et fenus magna sunt

Here magna is not directly attached to a noun inside a noun phrase; instead, it tells you something about the subject through the verb sunt.

Because Latin word order is much freer than English word order.

English usually wants something like:

• Freight and interest are great

Latin can place words in different positions without changing the basic grammar, because the endings show how the words function.

So Naulum et fenus magna sunt is perfectly normal. The adjective does not have to stand right beside the nouns.

Yes. Latin often allows several word orders, for example:

• Naulum et fenus magna sunt
• Magna sunt naulum et fenus
• Naulum et fenus sunt magna

These all mean essentially the same thing, though the emphasis may shift a little.

The version you have is a straightforward and natural one.

Because Latin has no definite article and no indefinite article.

So Latin does not normally have separate words for:

• the
• a
• an

That means naulum can mean freight, the freight, or a freight charge, depending on context. The same is true for fenus.

Et simply means and.

It links the two nouns:

• naulum et fenus = freight and interest

Because et joins them as two coordinated nouns, they become a plural subject.

No. Even though fenus ends in -us, it is actually a neuter noun, not masculine.

This can surprise English-speaking learners, because -us often suggests a masculine noun such as dominus. But fenus is an exception and is traditionally treated as a neuter noun.

So in this sentence, fenus helps cause the adjective to be neuter plural: magna.

Yes. Naulum is neuter as well.

So both nouns in the sentence are neuter:

• naulum = neuter
• fenus = neuter

That is why the predicate adjective is magna, the neuter plural form.

Latin often uses one adjective for a coordinated pair when that adjective applies to both nouns together.

So instead of saying something like naulum magnum et fenus magnum, Latin can simply say:

• Naulum et fenus magna sunt

This is more compact and natural: one plural adjective describes both items together.

A very literal breakdown would be:

• Naulum = freight / passage money
• et = and
• fenus = interest / usury
• magna = great / large / important
• sunt = are

So, word-for-word:

• Freight and interest great are

But natural English puts the verb before the adjective:

• Freight and interest are great

This is a very common question. Magna can indeed be more than one thing, depending on context.

It can be:

• feminine singular nominative
• feminine singular ablative
• neuter plural nominative
• neuter plural accusative

In this sentence, the context tells you it must be neuter plural nominative, because it agrees with naulum et fenus, which together form a plural neuter subject.

So the verb and subject help you identify the form.

The key lesson is this:

When two singular nouns are joined by et, they usually form a plural subject, so Latin uses:

• a plural verb
• and any predicate adjective must also agree appropriately

In this sentence:

• naulum et fenus = compound subject
• sunt = plural verb
• magna = neuter plural adjective agreeing with the combined subject

So the sentence is a good example of agreement with a compound subject.