Ο διαγωνισμός αρχίζει αύριο.

Ο is the definite article for a masculine singular noun in the nominative case. It means the.

So in ο διαγωνισμός, both words match:

• ο = masculine singular nominative the
• διαγωνισμός = masculine singular nominative competition / contest

Greek articles change form much more than English the does.

Διαγωνισμός is the dictionary form of the noun here: masculine singular nominative.

The ending -ος is very common for masculine nouns in Greek. In this sentence, the noun is the subject, so the nominative form is used.

A learner does not need to memorize every ending at once, but it helps to notice:

• ο διαγωνισμός = the competition/contest
• the article ο and the noun ending -ος are a very common masculine pattern

Αρχίζει is a verb. It is the 3rd person singular present tense form of αρχίζω, meaning to begin / to start.

So:

• αρχίζω = I start / I begin
• αρχίζει = he/she/it starts, or it begins

In this sentence, the subject is ο διαγωνισμός, so αρχίζει means the competition starts / begins.

Greek often uses the present tense for a scheduled or expected future event, just like English does.

Compare English:

• The competition starts tomorrow.

That is present tense in English, but it refers to the future. Greek works the same way here:

• Ο διαγωνισμός αρχίζει αύριο.

This sounds natural, especially for timetables, plans, and scheduled events.

Yes. That is also correct.

• Ο διαγωνισμός αρχίζει αύριο = The competition starts tomorrow.
• Ο διαγωνισμός θα αρχίσει αύριο = The competition will start tomorrow.

The first version can sound a bit more like a scheduled event.
The second uses the explicit future marker θα and is also very common.

So both are natural; the choice depends on style and context.

Αύριο is an adverb of time. It means tomorrow.

It does not change form here. It simply tells you when the action happens:

• αρχίζει = starts
• αύριο = tomorrow

So αύριο answers the question when?

Greek usually does not need subject pronouns when the subject is already clear.

In this sentence, the subject is explicitly stated:

• Ο διαγωνισμός = the competition

So Greek does not need an extra word like English it. The verb already agrees with the subject:

• ο διαγωνισμός αρχίζει

Greek often leaves out pronouns unless they are needed for emphasis or contrast.

Yes. Greek word order is more flexible than English word order.

The neutral order here is:

• Ο διαγωνισμός αρχίζει αύριο.

But you could also say:

• Αύριο αρχίζει ο διαγωνισμός.

That version puts more emphasis on tomorrow.

Because Greek marks grammatical relationships with articles and endings, word order can shift more easily than in English. The meaning usually stays the same, but the emphasis changes.

A simple learner-friendly pronunciation guide is:

• διαγωνισμός ≈ thee-a-go-neez-MOS
• αρχίζει ≈ ar-HEE-zee or more accurately ar-KHEE-zee with a soft throaty sound

A few useful notes:

• The accent mark shows the stressed syllable:
  • διαγωνισμός
  • αρχίζει
  • αύριο
• Greek χ in αρχίζει is not like English ch in chair. It is a harsher sound, somewhat like the German ch.
• Greek γ in διαγωνισμός before ο is not like English hard g in go; it is a voiced fricative sound.

For most beginners, getting the stress right is the most important first step.

The base form is αρχίζω = to begin / to start.

The present tense form here is regular enough for a learner:

• αρχίζω = I start
• αρχίζεις = you start
• αρχίζει = he/she/it starts

One thing worth noticing is that Greek often uses a different stem in the future/simple past:

• present-style: αρχίζω
• future/simple form: θα αρχίσω or θα αρχίσει depending on the subject

So a learner may see both αρχίζει and θα αρχίσει and wonder why they look slightly different. That is normal.

Usually διαγωνισμός means competition or contest.

Depending on context, it can also refer to a test or exam-like assessment, especially in educational settings. Greek words often cover a range that does not match English perfectly one-to-one.

So the exact English translation depends on context, but the Greek sentence structure stays the same.

Normally, you would keep the article:

• Ο διαγωνισμός αρχίζει αύριο.

Leaving it out can sound unnatural unless you are using a headline style, notes, labels, or a very special context.

So for ordinary full sentences, it is best to include ο when you mean the competition.

It is in the nominative case because it is the subject of the sentence.

That matters because Greek nouns and articles change form depending on their role in the sentence. Here:

• ο = nominative masculine singular article
• διαγωνισμός = nominative masculine singular noun

A beginner does not need to analyze every sentence in full detail, but recognizing that subjects usually appear in the nominative is very helpful as you learn Greek grammar.