Si augurium malum est, nautae in portu manent.

Si means if. It introduces a condition:

• Si augurium malum est = If the omen is bad

This is a very common way to form an if-clause in Latin.

Because augurium is a neuter singular noun, and the adjective must agree with it in gender, number, and case.

So:

• augurium = neuter singular
• malum = neuter singular nominative

That is why Latin uses malum, not malus.

A learner may recognize malus as bad, but that is only the masculine singular form. Latin adjectives change form depending on the noun they describe.

It is nominative singular.

In this clause:

• augurium = the subject
• est = is
• malum = adjective describing the subject

So augurium malum est literally means the omen is bad.

Here malum is a predicate adjective, not a direct object.

With forms of esse (to be), Latin often uses:

• subject in the nominative
• predicate noun/adjective also in the nominative

So:

• augurium = nominative subject
• malum = nominative adjective linked by est

This is just like English the omen is bad, where bad describes the subject rather than receiving the action.

Yes. Nautae can mean more than one thing depending on context.

Possible meanings include:

• nominative plural = sailors
• genitive singular = of the sailor
• dative singular = to/for the sailor
• vocative plural = O sailors

In this sentence, nautae must be nominative plural, because it is the subject of manent:

• nautae ... manent = the sailors remain/stay

Because nauta is a first-declension noun, even though it refers to a male person.

Some Latin nouns for male people use first-declension endings, for example:

• nauta = sailor
• poēta = poet
• agricola = farmer

So nautae is perfectly normal as the plural form, even though the sailors are male.

Because in can take different cases depending on the meaning.

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

Here the sailors are staying in the harbor, not moving into it:

• in portu = in the harbor

If the idea were they go into the harbor, Latin would use in portum.

Portu is ablative singular of portus, a fourth-declension noun.

Its main forms are:

• nominative singular: portus
• genitive singular: portūs
• accusative singular: portum
• ablative singular: portū

After in meaning in/at, Latin uses the ablative, so:

• in portu = in the harbor

In many textbooks the ablative is written portū with a long mark, but it is often printed simply as portu.

Both are present tense.

• est = is
• manent = they remain / they stay

So the sentence describes a general present situation:

• If the omen is bad, the sailors stay in the harbor.

It can also sound like a general rule or habitual action, which is common with present tense in both Latin and English.

Because its subject, nautae, is plural.

• nautae = the sailors
• manent = they remain

Latin verbs change form to match the subject in person and number. Since the subject is third person plural, the verb is also third person plural.

Yes. Latin word order is much freer than English word order because the endings show the grammar.

This sentence could appear in other orders, for example:

• Nautae in portu manent, si augurium malum est.
• Si malum augurium est, nautae in portu manent.

These still mean essentially the same thing.

That said, the given order is very natural:

• condition first: Si augurium malum est
• main clause second: nautae in portu manent

It can mean either, depending on how naturally you want to translate it.

• manent literally means they remain
• in smoother English here, they stay is often more natural

So both are good understandings:

• the sailors remain in the harbor
• the sailors stay in the harbor

It is a basic simple condition:

• si
  • present indicative
• main clause in the present indicative

Latin often uses this structure for ordinary real or general conditions.

So this sentence means something like:

• If the omen is bad, the sailors stay in the harbor

It does not suggest anything unreal or contrary to fact. It presents the condition as a normal possibility or general rule.