Learn Hardcore Greek: Η λάμπα στο γραφείο είναι η πιο δυνατή και φωτίζει όλο το δωμάτιο. - The lamp in the office is the strongest and lights up the whole room.

In Greek, every noun has a grammatical gender: masculine, feminine, or neuter.
The word λάμπα (lamp) is feminine, so it takes the feminine definite article:

η λάμπα = the lamp (feminine)
ο υπολογιστής = the computer (masculine)
το γραφείο = the desk / office (neuter)

The article must agree with the noun in gender, number, and case, so we say η λάμπα, not ο λάμπα or το λάμπα.

What exactly does στο mean in στο γραφείο, and how is it formed?

στο is a contraction of:

σε (in / at / on) + το (the, neuter singular) → στο

So:

σε + το γραφείο → στο γραφείο = on the desk / at the office

Other common contractions with σε are:

σε + τον → στον (στον δρόμο = in/on the road)
σε + τη(ν) → στη / στην (στην πόλη = in the city)
σε + τα → στα (στα σπίτια = in the houses)

So στο is “in/at/on the + [neuter noun]” in one word.

Does στο γραφείο mean on the desk or at the office? How can I tell?

The noun γραφείο can mean both:

το γραφείο = the desk
το γραφείο = the office

The preposition σε is also broad: it can mean in, at, on depending on context.

So στο γραφείο can mean:

on the desk (physical desk)
at the office (workplace)

In this specific sentence:

Η λάμπα στο γραφείο είναι η πιο δυνατή…

we naturally understand στο γραφείο as on the desk, because lamps are usually on a desk, not at an office as a location. Context (what is realistic) tells you which meaning is intended.

Why do we say είναι η πιο δυνατή instead of using a single word like δυνατότερη?

Modern Greek usually forms the comparative and superlative with πιο + adjective, instead of the “-ότερος” forms:

πιο δυνατή = stronger / more powerful / brighter
η πιο δυνατή = the strongest / the most powerful / the brightest

The form δυνατότερη is grammatically correct, but:

it sounds more formal or old-fashioned in many contexts
everyday speech prefers πιο δυνατή

So:

είναι η πιο δυνατή = “is the strongest/brightest”
είναι δυνατότερη would be understood, but is less common in casual modern usage.

Why is there another article η before πιο δυνατή? Could I say …είναι πιο δυνατή without it?

Both are possible, but the meaning changes.

είναι πιο δυνατή = “it is stronger/brighter” (comparative, but we don’t say than what)
είναι η πιο δυνατή = “it is the strongest/brightest” (superlative: the best one of a group)

The article η turns πιο δυνατή into a superlative (“the most X”). So in this sentence:

Η λάμπα στο γραφείο είναι η πιο δυνατή…

we are saying “the lamp on the desk is the strongest/brightest one (of all the lamps)”, not just “stronger” than something else.

So yes, you can say είναι πιο δυνατή, but then you mean “it is stronger/brighter (than something)”, not “the strongest/brightest”.

What does the adjective δυνατή literally mean, and why is it used for a lamp?

The basic adjective is δυνατός, -ή, -ό:

masculine: δυνατός
feminine: δυνατή
neuter: δυνατό

Its core meaning is strong / powerful. Depending on context, it can mean:

physical strength: ένας δυνατός άντρας = a strong man
intensity of sound: δυνατή μουσική = loud music
power / performance: μια δυνατή μηχανή = a powerful engine
intensity of light: μια δυνατή λάμπα = a bright / powerful lamp

So with a lamp, δυνατή λάμπα naturally means a bright lamp, i.e. one with strong light.

What form of the verb is φωτίζει? Which person, number, and tense is it?

The verb is φωτίζω = to light (up), to illuminate.

φωτίζει is:

person: 3rd person
number: singular
tense/aspect: present (imperfective)
voice: active

So φωτίζει means “he/she/it lights / is lighting / illuminates”.

In this sentence, the subject is η λάμπα, so:

η λάμπα φωτίζει = “the lamp lights / illuminates”

Can φωτίζει mean both “lights” and “is lighting” in English?

Yes.

Greek present tense (φωτίζει) normally covers both:

simple present: “it lights / it illuminates”
present continuous: “it is lighting / is illuminating”

So:

Η λάμπα φωτίζει όλο το δωμάτιο.
→ “The lamp lights the whole room.”
→ “The lamp is lighting the whole room.”

Both translations are valid; the difference in English is aspect, but Greek uses the same present form for both, and context tells you which English form feels more natural.

In όλο το δωμάτιο, why is it όλο and το and not some other endings?

The noun δωμάτιο (room) is neuter. In the accusative singular (used for the object of the verb), the definite article is το:

(βλέπω) το δωμάτιο = (I see) the room

The adjective όλος (whole, all) must agree with the noun:

masculine: όλος (όλο τον τοίχο = the whole wall)
feminine: όλη (όλη την πόλη = the whole city)
neuter: όλο (όλο το δωμάτιο = the whole room)

So we get:

όλο (neuter acc. sg. of the adjective)
το (neuter acc. sg. article)
δωμάτιο (neuter acc. sg. noun)

→ όλο το δωμάτιο = the whole room / all of the room

Can I change the word order, for example: Η λάμπα είναι η πιο δυνατή στο γραφείο και φωτίζει όλο το δωμάτιο? Does it still mean the same?

Yes, that sentence is grammatically correct, but the nuance can shift a bit.

Original:
- Η λάμπα στο γραφείο είναι η πιο δυνατή…
  Here στο γραφείο is attached to η λάμπα. It sounds like:
  - “The lamp on the desk is the brightest…”
Reordered:
- Η λάμπα είναι η πιο δυνατή στο γραφείο…
  Here στο γραφείο tends to attach to η πιο δυνατή, and can be understood as:
  - “The lamp is the brightest in the office…”

In many real contexts, both might be understood roughly the same, but:

Η λάμπα στο γραφείο → describes which lamp (the one on the desk)
η πιο δυνατή στο γραφείο → describes where it is the brightest (in the office)

So word order is flexible, but it slightly changes which part στο γραφείο seems to qualify.

Why do we need the verb είναι here? Could Greek drop it like some other languages do?

In standard, full sentences in modern Greek, the verb είμαι (“to be”) is normally required in the present tense:

Η λάμπα στο γραφείο είναι η πιο δυνατή. ✅
Η λάμπα στο γραφείο η πιο δυνατή. ❌ (sounds wrong in normal speech)

Greek sometimes drops είναι in:

headlines
very short informal phrases
fixed expressions

e.g. Ο καιρός καλός in a headline. But in regular spoken or written sentences, you should include είναι:

Η λάμπα στο γραφείο είναι η πιο δυνατή…

Why is the article το used with δωμάτιο? Could I say just φωτίζει όλο δωμάτιο?

You normally cannot drop the article here; φωτίζει όλο δωμάτιο sounds ungrammatical.

In Greek, definite nouns almost always take the definite article, even where English can drop “the”. After όλος (whole/all), the noun is generally definite and takes the article:

όλο τον κόσμο = the whole world
όλο το βράδυ = the whole evening
όλο το δωμάτιο = the whole room

So the natural form is:

φωτίζει όλο το δωμάτιο ✅
φωτίζει όλο δωμάτιο ❌

How would I use this structure to say “the brightest lamp in the room” in Greek?

You can use the same η πιο + adjective pattern:

Using δυνατή (everyday, “powerful/bright”):
- η πιο δυνατή λάμπα στο δωμάτιο
  = the brightest / most powerful lamp in the room
If you want a more explicitly “luminous” word, use φωτεινή (bright, full of light):
- η πιο φωτεινή λάμπα στο δωμάτιο
  = the brightest lamp in the room

Both are natural; η πιο δυνατή λάμπα is very common in casual speech for “the brightest lamp”.