Learn Hardcore Dutch: De zaal is vol.

Because zaal is a common‑gender noun (a de‑word), so it takes de. The indefinite form is een zaal. There is no reliable rule from the ending; you just learn that zaal is a de‑word (unlike, for example, het lokaal).

What exactly does zaal mean compared to kamer, hal, or ruimte?

zaal: a large room used for gatherings/events, e.g. a theater hall, cinema auditorium, gym, museum gallery. Examples: de theaterzaal, zaal 3, de sportzaal.
kamer: a (usually smaller) room in a house or building, e.g. slaapkamer, vergaderkamer.
hal: a hall/entryway or large concourse, especially near an entrance, e.g. de ingangshal.
ruimte: space/room (more general/abstract), not necessarily a distinct room with walls.

Is vol an adjective here, and does it change form?

Yes. vol is a predicative adjective after the copula is. Predicative adjectives don’t take the -e ending, regardless of gender/number:

De zaal is vol.
De zalen zijn vol.
No change to vol.

How do I say the full hall versus the hall is full?

Predicative (after a verb): De zaal is vol. (no -e)
Attributive (before a noun): de volle zaal, een volle zaal (adjective gets -e here)
Note the neuter exception: with a neuter singular noun without article de/het, no -e: een vol huis (but het volle huis).

How do I negate it: niet or geen?

Use niet, because you’re negating an adjective: De zaal is niet vol.
Use geen only to negate a noun: Er is geen zaal (There is no hall).

Are there more natural verbs than is with vol?

Yes, Dutch often uses posture or motion verbs for nuance:

De zaal zit vol (met mensen). — seats are all taken; very idiomatic with people.
De zaal staat vol (met stoelen). — full of things that stand.
De vloer ligt vol (met papieren). — full of things that lie.
Process: De zaal loopt vol. / De zaal is volgelopen.

How do I say what it’s full of?

De zaal is vol mensen.
De zaal is vol met mensen. (very common in speech; both are accepted)
Most idiomatic with people: De zaal zit vol met mensen.

Does De zaal is vol also mean a show is sold out?

It describes the physical state. For ticket/booking status use:

De voorstelling is uitverkocht. (sold out)
Het hotel is volgeboekt. / Het hotel zit vol. (fully booked)

How do I pronounce it?

de: [də] (schwa)
zaal: [zaːl] (long aa like the a in father)
is: [ɪs] (short i)
vol: [vɔl] (short o as in British lot; v is voiced)
Main stress on zaal and vol.

What about questions and word order?

Yes/no question: Is de zaal vol?
Subordinate clause: … dat de zaal vol is.
Fronting for emphasis like Vol is de zaal is possible but literary; normal speech keeps De zaal is vol.

How do I say it in other tenses?

Past: De zaal was vol.
Future: De zaal zal vol zijn.
Note the difference between zaal (hall) and zal (will); they look similar but mean different things.

What are common intensifiers or near‑synonyms for vol?

helemaal vol, hartstikke vol (very full)
bomvol, propvol, stampvol (colloquial: packed)
overvol (overfull, beyond capacity)
Comparatives exist but are less common: voller, het volst(e).

Any useful idioms with zaal?

volle zalen trekken — to draw big audiences
voor een volle zaal spelen — to perform to a full house

How do I express busyness versus fullness?

Full: De zaal is vol.
Busy/crowded: use druk with an impersonal construction: Het is druk in de zaal.
Avoid De zaal is druk for this meaning.

Can I say this about people or things other than rooms?

Yes, vol is widely used:

Mijn agenda zit vol. (my schedule is packed)
Mijn telefoon is vol. (storage full)
After eating: Ik zit vol. or Ik ben volgegeten. Avoid Ik ben vol for this meaning.

Is it normal to drop the article or contract words?

Standard Dutch keeps the article: De zaal is vol. You don’t contract is (no De zaal’s vol). In signs or headlines you might see elliptical forms like Zaal vol, but that’s not full‑sentence standard usage.