Learn Hardcore Turkish: Gerekirse toplantıyı uzatırız; değilse zamanında biter. - If necessary, we will extend the meeting; otherwise, it will end on time.

-se/-sa is the conditional “if.”
gerek-ir-se = “if it is necessary,” from gerekmek (aorist 3sg gerekir “it is necessary” + conditional).
It functions as a set phrase meaning “if necessary.”

Can I say gerekliyse instead of gerekirse? Any nuance difference?

Yes.

gerekliyse = “if [it is] necessary,” built from the adjective gerekli
- buffer y
  - -se.
gerekirse (from the verb gerekmek) is more idiomatic and modal-sounding in this context.
Both are correct; gerekirse is the more common quick way to say “if necessary.”

Why is it uzatırız (aorist) and not future uzatacağız? Does it still mean “we’ll extend (it)”?

Yes. In conditional sentences, Turkish often uses the aorist to express future outcomes, rules, or policies.

uzatırız = neutral policy/decision (“we’ll extend it [if that condition holds]”).
uzatacağız = a more definite plan or commitment.
Both are possible; the aorist is stylistically very natural here.

Would uzatabiliriz work? What changes in meaning?

Uzatabiliriz = “we can/could extend [it],” adding ability/possibility and sounding more tentative or polite.

Gerekirse uzatırız: firmer, matter-of-fact policy.
Gerekirse uzatabiliriz: softer, offers the option.

Why is it toplantıyı (accusative) and not just toplantı?

Because uzatmak is transitive (“to extend [something]”), so its object takes the definite accusative when specific: toplantı-y-ı.

The -y- is a buffer consonant between the vowel-ending noun and the suffix -ı.
If you switch to intransitive uzamak (“to get longer”), you’d say: Toplantı uzar (“The meeting runs long”).

What does zamanında mean exactly, and how is it formed?

It means “on time / in due time.”
Morphology: zaman-ı-n-da = “in its time” (noun + 3sg possessive + locative, with buffer -n-).
Common synonyms: vaktinde, tam zamanında.

Why biter and not bitiririz? Who is the subject?

biter is intransitive (“it ends/finishes”), 3sg aorist; the subject is the meeting (understood from context).
bitiririz is transitive (“we finish [it]”).
Both are grammatical, but the original contrasts an action we might take (extend it) with the meeting ending on its own (ends on time).

What exactly is değilse? How can değil take -se?

değil is the negation of the copula “to be.” Adding -se makes it conditional: değil-se = “if not.”
Here it’s elliptical: “if not (so/that),” i.e., “otherwise.” It refers back to the prior condition without repeating it.

Can I use yoksa or aksi takdirde instead of değilse?

Yes:

yoksa ≈ “otherwise / or else,” common and slightly more conversational.
aksi takdirde (or aksi halde) = “otherwise,” more formal.
All work here: they introduce the alternative outcome if the first condition isn’t met.

Is the semicolon necessary? Could I use a comma or a period?

The semicolon neatly separates two balanced clauses. You could also write:

Gerekirse toplantıyı uzatırız, değilse zamanında biter.
Gerekirse toplantıyı uzatırız. Değilse, zamanında biter.
All are acceptable; punctuation is stylistic here.

Would Gerekmezse be better for symmetry: Gerekirse …; gerekmezse …?

That’s perfectly good and nicely parallel:

Gerekirse toplantıyı uzatırız; gerekmezse zamanında biter.
Using değilse is just a shorter, very common way to say “if not/otherwise.”

Why isn’t the pronoun biz written? How do we know it means “we”?

Turkish marks person/number on the verb: uzat-ır-ız (stem + aorist + 1pl). Because the ending already shows “we,” biz is optional and used mainly for emphasis.

Any pronunciation tips for tricky bits like ı and the suffixes?

ı (dotless i) is a back, unrounded vowel (like the ‘e’ in “taken” but further back): to-plan-tı-yı = [toh-plahn-tuh-yuh].
Suffix vowels obey vowel harmony: -ı after back vowels (as in toplantı-y-ı), -i after front vowels, etc.
Stress typically falls on the last syllable of words, but fixed phrases like zamanında are often pronounced fluidly as a single adverb.

Can I put the object after the verb: Uzatırız toplantıyı?

You can, but the neutral order is object before verb: Toplantıyı uzatırız. Post‑verbal objects are used for special emphasis/focus and are less neutral in tone.

Could I say Gerektiğinde toplantıyı uzatırız? Is it different from gerekirse?

Yes. Gerektiğinde = “when necessary” (time-based “when”), while gerekirse = “if necessary” (condition-based “if”). In practice they’re often interchangeable here; gerekirse is a bit crisper in conditional statements.