Forum frequens hodie est.

Because the sentence means The forum is crowded today, so forum is the thing being described.

A point that often confuses beginners is that forum looks like it could be accusative, because in second-declension neuter nouns the nominative singular and accusative singular are the same. So:

• forum can mean the forum as a subject
• forum can also mean the forum as a direct object

In this sentence, est (is) shows that forum is the subject of a linking verb, so forum is nominative here.

Here frequens means something like:

• crowded
• full
• well-attended
• busy

So Forum frequens hodie est means The forum is crowded today or The forum is busy today.

This can be tricky for English speakers because frequens is related to English frequent, but it does not mean exactly the same thing in this sentence. In Latin, frequens often describes a place or gathering as being full of people.

Because it is a predicate adjective.

With a linking verb like est (is), Latin uses an adjective in the nominative to describe the subject. So:

• forum = subject, nominative singular
• frequens = adjective describing the subject, also nominative singular

This is just like in English:

• The forum is crowded

Here crowded describes the forum, not an object.

Because frequens is the correct nominative singular form of this adjective.

It is a third-declension adjective with the dictionary form:

• frequens, frequentis

This adjective has one nominative singular form for all genders, so the same frequens can be used with:

• masculine singular
• feminine singular
• neuter singular

Since forum is neuter singular, frequens is also singular and nominative, and the form happens to stay frequens.

In this sentence, it is part of the predicate.

So the structure is:

• Forum = subject
• hodie = adverb
• est = linking verb
• frequens = predicate adjective

In other words, the sentence is not quite the crowded forum today is; it is the forum is crowded today.

Latin often allows word order that makes an adjective appear close to the noun even when it is really predicate, but the presence of est makes the function clear here.

Hodie is an adverb meaning today.

It tells you when the statement is true:

• Forum frequens hodie est = The forum is crowded today

Since it is an adverb, it does not have to agree with any noun. It simply adds time information to the whole statement.

Because Latin word order is much more flexible than English word order.

The sentence could also be written in other ways, such as:

• Hodie forum frequens est
• Forum hodie frequens est
• Forum est hodie frequens

All of these can mean essentially the same thing.

The version Forum frequens hodie est may slightly emphasize forum first, then crowded, and finally finish with is, which is a very normal Latin style.

Because Latin very often places the verb near or at the end of the sentence.

This is one of the most common word-order patterns in Latin, though it is not a fixed rule. So:

• Forum frequens hodie est

sounds perfectly natural in Latin, even though in English we normally say:

• The forum is crowded today

So the final est is normal Latin style, not something unusual.

Because Classical Latin has no definite article and no indefinite article.

So forum can mean:

• the forum
• a forum

The context tells you which English translation is best. In this sentence, English usually wants the forum.

Forum is a second-declension neuter noun.

Its basic form is:

• forum, fori

Important things to remember about neuter second-declension nouns:

• nominative singular ends in -um
• accusative singular is also -um
• nominative plural ends in -a
• accusative plural also ends in -a

So forum here is a very typical neuter singular form.

Yes.

In Roman context, forum usually means the public square, marketplace, or civic center of a town, not an online discussion board or just any meeting place.

So in this sentence, the image is probably something like:

• the town square is busy today
• the public marketplace is full of people today

That helps explain why frequens means crowded here.

Not necessarily.

Because of hodie (today), the sentence clearly describes a situation true today, not an always-true fact.

So it means something like:

• The forum is crowded today
• not The forum is generally a crowded place by nature

The adverb makes the statement temporary and time-specific.

Yes, much more freely than English can.

English depends heavily on word order, but Latin depends more on endings. Since forum and frequens are both nominative singular, and hodie is obviously an adverb, the meaning stays clear even when the words move around.

That is why a Latin learner should focus less on strict English-like order and more on:

• case endings
• agreement
• the function of the verb

Those are what tell you how the sentence works.