Learn Hardcore Turkish: Bugün durak bayağı kalabalık. - Today the bus stop is quite crowded.

durak (subject) + bayağı (intensifier) + kalabalık (predicate adjective) = “the stop is quite crowded.” There is no visible copula in third person singular/plural present. For 1st/2nd person you do see personal endings (e.g., yorgunum, yorgunsun). A formal/inferential ending -dır/-dir can appear (see below).

Shouldn’t it be durakta (at the stop) instead of durak?

Both can be correct but they say slightly different things:

Bugün durak bayağı kalabalık. “The stop is quite crowded.” The stop itself is the topic; the adjective describes its state.
Bugün durakta kalabalık var. “There is a crowd at the stop today.” Locative -ta/-te pairs well with existential var/yok.
You can also say: Bugün durakta çok kişi/insan var. Avoid forms like Durakta çok kalabalık var; prefer büyük bir kalabalık var or use an adjective predicate: Durak çok kalabalık.

What exactly does bayağı mean here?

Here bayağı is an adverb meaning “quite/pretty/rather,” a fairly strong intensifier but softer than çok (very). Rough scale (from milder to stronger, context-dependent): biraz < epey/oldukça/hayli ≈ bayağı < çok/çok fazla. It’s common and colloquial-neutral in speech.

Is bayağı ever negative, like “vulgar/low”?

Yes, as an adjective it can mean “vulgar/common/low-quality” (e.g., bayağı bir zevk). In your sentence it’s an adverb before an adjective (bayağı kalabalık) and simply means “quite,” with no negative tone.

How do I pronounce bayağı and Bugün? What does ğ do?

bayağı: The ğ is a “soft g” that lengthens the preceding vowel; it’s not pronounced like an English g. So it’s roughly “ba-yaa,” and the final ı is the Turkish dotless ı (a close, unrounded sound, like the a in “sofa”). Many people say it colloquially as baya.
Bugün: “boo-gün,” with ü as a front rounded vowel (like French u or German ü).

Why is there no article before durak? Should it be “the stop” or “a stop”?

Turkish has no articles like “the”/“a.” Definiteness comes from context, word order, and case. Here durak is a specific, contextually known stop (“the stop”). If you wanted to introduce a non-specific one, you could use bir (e.g., bir durak), but that would sound odd in this sentence.

Can I change the word order?

Yes—word order is flexible for emphasis:

Bugün durak bayağı kalabalık. Neutral; highlights “today” first.
Durak bugün bayağı kalabalık. Emphasizes the stop, then specifies “today.”
Bayağı kalabalık bugün durak. Possible in speech for dramatic emphasis, but much less neutral. Stick to the first two for standard style.

How do I negate this?

Use değil with adjective predicates:

Bugün durak kalabalık değil. “The stop isn’t crowded today.” For “not very,” add pek: Bugün durak pek kalabalık değil.

Can I use çok instead of bayağı?

Yes:

Bugün durak çok kalabalık. = “very crowded” (stronger, neutral).
Bugün durak bayağı kalabalık. = “quite/pretty crowded” (slightly softer, conversational).

Is kalabalık an adjective or a noun?

Both, depending on use:

Adjective: durak kalabalık = “the stop is crowded.”
Noun: kalabalık = “a crowd.” Example: Bugün durakta büyük bir kalabalık var. = “There is a big crowd at the stop today.”

How does plural agreement work? Would I say Duraklar kalabalık or kalabalıklar?

Predicate adjectives don’t agree in number. Say:

Duraklar bayağı kalabalık. “The stops are quite crowded.” Using kalabalıklar would mean “crowds,” changing the meaning.

Can I add -dır/-dir (the formal/inferential ending): Bugün durak bayağı kalabalıktır?

Grammatically possible, but it usually sounds formal or inferential (“I presume the stop is quite crowded today”). With bugün, most speakers prefer the plain form. Use -dır for general truths or when you’re inferring rather than directly observing.

What about oluyor: Bugün durak bayağı kalabalık oluyor?

That emphasizes a developing/recurring state: “It’s (turning out to be / tends to be) quite crowded today (these days, lately).” The simple kalabalık states the current condition; oluyor adds a sense of change or pattern.

Do I ever need bir after bayağı?

With an adjective predicate, no: bayağı kalabalık (correct).
With a noun, yes it’s common: bayağı bir kalabalık var = “there is quite a (big) crowd.” Colloquial speech also says baya bi’ for bayağı bir.

How do I add cases to durak? Any spelling changes?

Yes, the final k often softens to ğ before vowel-initial suffixes:

Locative: durakta (“at the stop”)
Dative: durağa (“to the stop”) k → ğ
Ablative: duraktan (“from the stop”)
Genitive: durağın (“of the stop”) k → ğ

Is it ever written bu gün instead of bugün?

Standard modern Turkish writes it as one word: bugün.