Learn Hardcore Greek: Ευχαριστώ.

IPA: [efxaɾisˈto]
Rough guide: ef-kha-ree-STOH (kh like the ch in German Bach or Spanish jota; r is a quick tap).
The ευ here sounds like ef because it’s before a voiceless consonant (χ). Before voiced sounds it becomes ev (e.g., Ευβοία = ev-).
Stress is on the last syllable: -στώ.

What does the accent mark on Ευχαριστώ do? Do I need to write it?

The accent (τόνος) shows which syllable is stressed. In Ευχαριστώ, it’s on ώ.
Yes, in standard writing you should include it on words with two or more syllables: Ευχαριστώ.
If the whole word is in ALL CAPS, the accent is commonly omitted: ΕΥΧΑΡΙΣΤΩ. Otherwise, keep it.

Is Ευχαριστώ literally “I thank”? Is it a full sentence?

Yes. Ευχαριστώ is the 1st person singular present of the verb meaning “I thank.”
Greek drops subject pronouns, so Ευχαριστώ alone is a complete sentence (“I thank [you]”).
For emphasis you can say Εγώ ευχαριστώ! meaning “No, thank YOU!”

Do I need to say “you”? What’s the difference between Σε ευχαριστώ and Σας ευχαριστώ?

You don’t have to; Ευχαριστώ already implies “you.”
Σε ευχαριστώ = “I thank you” (informal singular). Before a vowel it often contracts to Σ’ ευχαριστώ.
Σας ευχαριστώ = “I thank you” (polite singular or plural).
The object pronoun goes before the verb in Greek. Don’t say Ευχαριστώ σε.

How do I say “Thank you very much” or make it stronger?

Ευχαριστώ πολύ. = Thank you very much.
Stronger: Ευχαριστώ πάρα πολύ.
More formal: Σας ευχαριστώ πολύ. / Σας ευχαριστώ θερμά.
Colloquial emphasis (especially in writing): Χίλια ευχαριστώ! (“A thousand thanks!”)

What do people say in reply to Ευχαριστώ?

Can I use it to refuse politely, like “No, thanks”?

Yes: Όχι, ευχαριστώ.
You can soften further: Όχι, ευχαριστώ πολύ, but it may read a bit emphatic; tone of voice matters.
Example: Θέλεις καφέ; — Όχι, ευχαριστώ.

How do I say “Thanks for …” something?

With a noun: Ευχαριστώ για + [noun].
- Ευχαριστώ για τη βοήθεια. (Thanks for the help.)
- Σας ευχαριστώ για το δώρο.
With a whole clause: Ευχαριστώ που + [clause].
- Σε ευχαριστώ που ήρθες. (Thanks for coming.)
- Σας ευχαριστώ που περιμένατε.
Don’t say “για που”; use που after the verb.

What are the other forms (we thank, you thank, etc.)?

Present tense:

εγώ ευχαριστώ (I thank)
εσύ ευχαριστείς (you sg.)
αυτός/ή/ό ευχαριστεί (he/she/it)
εμείς ευχαριστούμε (we)
εσείς ευχαριστείτε (you pl./polite)
αυτοί/ές/ά ευχαριστούν(ε) (they) — the final -ε is optional in speech From a group you’ll often hear Ευχαριστούμε! (“We thank you/Thanks!”)

Why is it written with ω (omega) and not ο? Do they sound different?

In Modern Greek, ο and ω sound the same (“o”).
The -ώ ending (omega with accent) is a standard spelling for many 1st person singular present-tense verbs (e.g., μπορώ, αγαπώ). It’s an orthographic pattern, not a pronunciation difference.

Is Ευχαριστώ related to the English word “Eucharist”?

Yes. ευ- (“good, well”) + χάρις (“grace, favor”) → ευχαριστία (“thanksgiving, gratitude”) → ευχαριστώ (“I thank”).
English Eucharist comes from this Greek root via “thanksgiving.”

Can Ευχαριστώ be sarcastic, like “Thanks a lot!”?

Yes. Ευχαριστώ πολύ! can be sarcastic depending on tone and context, just like in English. In writing, context and punctuation (e.g., “!”) carry the nuance.

What punctuation should I use with it?

Both Ευχαριστώ. and Ευχαριστώ! are common; the exclamation mark is frequent in friendly contexts.
Remember: in Greek, the “question mark” looks like a semicolon (;) — not relevant here, but useful to know so you don’t misread Ευχαριστώ; as a question.