Taberen er træt.

Because Danish usually shows the by adding it to the end of the noun.

• en taber = a loser
• taberen = the loser

The noun taber is a common-gender noun, so its definite singular ending is -en. If it were a neuter noun, the definite ending would usually be -et instead.

The dictionary form is taber.

That is the indefinite singular form, usually learned with its article:

• en taber = a loser

From that, you get:

• taberen = the loser

So when looking words up, you would search for taber, not taberen.

Er is the present tense of at være, which means to be.

So it works like English is in this sentence.

A useful thing to know is that Danish does not change this form for different persons in the present tense:

• jeg er = I am
• du er = you are
• han/hun er = he/she is
• vi er = we are

So er is used very broadly.

No, not in standard Danish.

You need the verb er here. So:

• Taberen er træt = correct
• Taberen træt = not standard Danish

Danish normally requires the verb to be in sentences like this.

Because here it is describing one person in a simple predicate after er.

In this sentence, træt is the correct singular form:

• Taberen er træt = The loser is tired

You usually get trætte when the subject is plural or when the adjective comes before a definite noun:

• De er trætte = They are tired
• den trætte taber = the tired loser

So træt is right here.

Taber is a common-gender noun.

That matters because Danish nouns have two grammatical genders:

• common gender
• neuter

The gender affects which article and endings you use. For taber:

• en taber = indefinite singular
• taberen = definite singular

If it were a neuter noun, you would expect et in the indefinite and often -et in the definite.

Not really. This sentence has very straightforward Danish word order:

• Taberen = subject
• er = verb
• træt = predicate adjective

So it follows the same basic pattern as English:

• subject + verb + complement

If you turn it into a yes/no question, Danish usually puts the verb first:

• Er taberen træt? = Is the loser tired?

You would say:

• En taber er træt

That uses the indefinite article en instead of the definite ending -en.

So compare:

• En taber er træt = A loser is tired
• Taberen er træt = The loser is tired

Because Danish often uses a different definite pattern when there is an adjective before the noun.

Without an adjective:

• taberen = the loser

With an adjective:

• den trætte taber = the tired loser

So Danish often uses both:

• a separate definite word like den
• and the noun in its definite form pattern

That is why Taberen er træt has no den, but den trætte taber does.

A learner-friendly approximation is:

• træt ≈ tret with a vowel somewhat like the a in cat, but Danish speakers usually make it sound more open and tense than English does

The letter æ is a very common Danish vowel, and English speakers often need practice with it.

For the whole sentence, a rough stress pattern is:

• TA-ber-en er træt

The stress is mainly on the first syllable of taberen.

Usually it means tired, sleepy, or worn out, depending on context.

It can also be used in expressions like:

• jeg er træt af det = I am tired of that

There it means more like fed up with or sick of.

But in Taberen er træt, the most natural reading is simply that the person is tired.