Dies festus omnibus gratus est.

Dies means day here. It is a 5th-declension noun, which is worth noticing because most Latin nouns are not in the 5th declension.

Its dictionary form is dies, diei.

A useful thing to know is that dies is often masculine, especially when it means an ordinary day or a specific appointed day. In some contexts it can be feminine, but in this sentence it is masculine.

That is why the adjective is festus, not festa.

Festus is an adjective meaning festive, holiday, or feast-day in sense.

It is masculine nominative singular because it agrees with dies, which is:

• masculine
• nominative
• singular

So:

• dies festus = a festival day / a holiday / a feast day

Latin adjectives normally agree with the nouns they describe in:

• gender
• number
• case

It is a normal Latin expression. Dies festus is a standard way to say holiday, festival day, or feast day.

So although literally it looks like festive day, it is better understood as a regular phrase meaning a day of celebration or observance.

Omnibus is dative because gratus often takes a dative of the person pleased.

So the structure is:

• X gratus est alicui = X is pleasing to someone
• literally: X is dear/pleasant/welcome to someone

Here:

• dies festus = the subject
• gratus est = is pleasing / welcome
• omnibus = to all / to everyone

So omnibus means to all people or to everyone.

Gratus is an adjective meaning pleasing, welcome, dear, or agreeable.

With est, it means:

• is pleasing
• is welcome
• is dear

So Dies festus omnibus gratus est literally means something like:

• A festival day is pleasing to everyone
• A holiday is welcome to everyone

Even if the meaning has already been given, this is the grammar behind it.

Because Latin usually shows relationships like to, for, with, and so on by case endings, not by separate words.

Here, English says:

• to everyone

Latin says:

• omnibus

The ending -ibus shows the dative plural (or ablative plural, depending on context). In this sentence, the meaning is clearly dative: to all.

Yes, omnibus by itself can mean:

• to all people
• to all things
• for all
• for everyone

The exact meaning depends on context.

In this sentence, the natural sense is to everyone, because a holiday is pleasing to everyone makes good sense. But grammatically, omnibus is simply dative plural of omnis, and the noun it refers to is not stated explicitly.

It comes from omnis, omne, meaning all or every.

Here it is dative plural:

• masculine/feminine dative plural: omnibus
• neuter dative plural: omnibus

So the same form can serve several genders in the plural.

In this sentence it means something like:

• to all people
• to everyone

Latin word order is much freer than English word order because the endings already show how the words function.

Putting est at the end is very common in Latin. In fact, the verb to be often comes late in the sentence.

So:

• Dies festus omnibus gratus est is a very natural Latin order.

Latin often places important descriptive words before the verb and leaves the verb to finish the statement.

Because dies is in the nominative singular, and festus agrees with it in nominative singular.

Also, gratus est is singular, so the subject should be singular too.

Meanwhile, omnibus is dative, so it cannot be the subject.

That gives us the structure:

• Dies festus = subject
• gratus est = predicate
• omnibus = dative with gratus

It is an adjective, not part of the verb.

The verb is only est.

Latin often uses:

• a form of sum (to be)
• plus an adjective

So gratus est literally means:

• is pleasing
• or more literally, is pleasant/welcome

This is similar to English sentences like:

• He is happy
• The book is useful

Here:

• The holiday is welcome to everyone

Yes. Depending on style, you could translate it as:

• A holiday is pleasing to everyone.
• A festival day is welcome to everyone.
• A feast day is dear to all.
• Everyone likes a holiday.

That last one is less literal, but it captures the idea well.

Latin often allows several good English translations, because one Latin adjective like gratus can overlap with several English words.

Latin has no articles like English a, an, or the.

So dies festus could mean, depending on context:

• a holiday
• the holiday
• holiday in a general sense

In this sentence, English usually supplies a holiday or a festival day, but Latin itself does not mark that difference.

Yes—this sentence is a good example of three very common Latin features:

1. Adjective agreement

   • festus agrees with dies
   • gratus also agrees with dies

2. Dative with certain adjectives

   • gratus alicui = pleasing to someone
   • here: omnibus

3. Flexible word order

   • English depends heavily on position
   • Latin depends more on endings

So this short sentence teaches a lot:

• identify the subject by case
• notice adjective agreement
• recognize the dative after gratus
• do not expect English-style word order