Learn Hardcore Turkish: Cüzdanını almadan dışarı çıkma, gerekebilir. - Don’t go out without taking your wallet; you might need it.

In the sentence, the idea is not just any wallet; it is your specific wallet. That is why you get cüzdanını and not just cüzdanın or bare cüzdan.

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

Almadan comes from almak (to take) + the converb ending -madan / -meden.

Structure:

al- – verb root (take)
-ma- – the negative marker
-dan – the ablative part of this converb

Function of -madan / -meden:
It forms an adverbial clause meaning without doing X or before doing X depending on context. Here it means without taking.

So:

almadan – without taking (it)

In the sentence:

cüzdanını almadan – without taking your wallet

This whole phrase functions like an adverbial: it modifies çıkma (do not go out).

Why is it almadan dışarı çıkma, and not something like almadan önce dışarı çıkma?

You could say almadan önce dışarı çıkma, but it would sound odd, because the meaning of -madan already covers the idea of before / without doing X.

Compare:

cüzdanını almadan dışarı çıkma – do not go out without taking your wallet
cüzdanını almadan önce dışarı çıkma – literally: do not go out before before taking your wallet (repetitive)

-madan already implies before in this negative, preventative context, so adding önce is usually redundant or unnatural here.

If you want to stress the sequence more clearly, you can instead use a positive form:

Cüzdanını aldıktan sonra dışarı çık. – Go out after you take your wallet.

What is the role of dışarı here? Why not dışarıya?

Dışarı literally means outside / out and often combines with motion verbs like çıkmak (to go out):

dışarı çıkmak – to go out (go outside)

This is a very fixed and natural collocation in Turkish.

Dışarıya is also grammatically possible (with -A direction suffix), but:

dışarı çıkmak is the default, everyday expression.
dışarıya çıkmak can sound a bit more explicit about direction (to the outside), but in practice many speakers prefer plain dışarı çıkmak.

So almadan dışarı çıkma is completely idiomatic; almadan dışarıya çıkma is not wrong, but less common in casual speech.

How does çıkma work as don’t go out here? Is this the negative imperative?

Yes. Çıkma here is the negative imperative (second person singular, informal).

Formation:

çık- – verb root (go out)
-ma – negative imperative ending (for 2nd person singular)

So:

çık! – go out!
çıkma! – do not go out!

In writing, both çıkma (don’t go out) and the noun çıkma (a small balcony, projection on a building) look the same. You distinguish them by context. Here it is clearly the verb form, because it follows an adverbial clause (cüzdanını almadan dışarı) and fits the meaning.

Is this sentence very strong or rude? How polite is the form çıkma?

Çıkma (bare negative imperative) is:

informal
direct
possibly a bit strong, depending on tone

It is appropriate for:

parents to children
close friends
someone with clear authority (teacher, boss, etc.) if the relationship allows direct commands

Softer alternatives:

Cüzdanını almadan dışarı çıkma bence. – Don’t go out without your wallet, in my opinion.
Cüzdanını almadan dışarı çıkma, iyi olmaz. – Don’t go out without your wallet, it wouldn’t be good.
Cüzdanını almadan dışarı çıkma istersen. – Maybe don’t go out without your wallet.

More polite plural/formal:

Cüzdanınızı almadan dışarı çıkmayın. – (polite or plural) Don’t go out without your wallet(s).

What does gerekebilir mean, and how is it formed?

Gerekebilir comes from gerek- (to be necessary) plus the potential and aorist markers:

gerek- – to be necessary
-e- – potential marker (can/may)
-bilir – (historically) the same potential marker you see in gelebilir (may come), but here it is merged and written as gerekebilir

Functionally, gerekebilir means:

it might be necessary
you might need it (depending on context)

The verb gerekmek is impersonal; you often see it with a subject:

Para gerekebilir. – Money might be necessary.
Cüzdanın gerekebilir. – Your wallet might be necessary / you might need your wallet.

In the original sentence, the subject is understood from context as cüzdanın (your wallet).

There is no onu or cüzdanın before gerekebilir. What is the subject of gerekebilir here?

The subject is not written, but it is understood from context.

Earlier in the sentence we have cüzdanını (your wallet, as object of almak). When we say gerekebilir after that, speakers naturally interpret:

(Cüzdanın) gerekebilir. – Your wallet might be necessary.

Turkish often drops elements that are clear from context:

Pronouns: (Ben) biliyorum. → I know.
Subjects: (Param) bitti. → My money is finished.
Objects: when just mentioned, can be omitted.

Here, cüzdanını was just mentioned, so cüzdanın as the subject of gerekebilir is easily inferred. That is why a simple gerekebilir is enough.

Why is there a comma before gerekebilir? Could this be two separate sentences?

The comma marks a natural pause and separates two clauses:

Cüzdanını almadan dışarı çıkma – Main clause; an imperative.
gerekebilir – Second clause; a comment/reason (it might be necessary).

You could write:

Cüzdanını almadan dışarı çıkma. Gerekebilir.

This is also correct. The choice between comma and full stop is mostly stylistic and related to how tightly you want to connect the ideas. With a comma, it feels like one flowing sentence; with a period, like a command followed by a separate justification.

Could I say this another way, for example using lazım or ihtiyaç?

Yes, very naturally. Some common alternatives:

Cüzdanını almadan dışarı çıkma, lazım olabilir.
– Don’t go out without your wallet; you might need it.
Cüzdanını almadan dışarı çıkma, cüzdanına ihtiyacın olabilir.
– Don’t go out without your wallet; you might need your wallet.
Cüzdanını almadan dışarı çıkma, cüzdanın gerekebilir.
– Don’t go out without your wallet; your wallet might be necessary.

Nuances:

gerekebilir and lazım olabilir are very close.
ihtiyacın olabilir is slightly more personal; it literally says you may have need (of it).

All of them sound natural in everyday speech.

Can I change the word order, like Dışarı cüzdanını almadan çıkma? Is that okay?

Some word order variation is possible, but not all orders sound equally natural.

Acceptable variants:

Cüzdanını almadan dışarı çıkma. (original; very natural)
Dışarı cüzdanını almadan çıkma. (also possible, but rarer; emphasis slightly shifts to dışarı.)

Less natural or odd:

Cüzdanını dışarı almadan çıkma. – Sounds wrong; it suggests take your wallet outside, which is not the intended structure.

General rule: keep dışarı çıkmak together as a unit if possible. When you insert almadan between them, it should clearly attach to çıkma, not to dışarı. So:

cüzdanını almadan [dışarı çıkma] is best.

Is -madan always negative? How is it different from something like almadan önce?

-madan / -meden is based on the negative stem (al-ma-, git-me-, etc.), so yes, it is inherently negative in form, but its meaning is not exactly not doing X; it more specifically means:

without doing X
or before doing X (when there is an implied sequence)

Examples:

Kahvaltı yapmadan işe gitme. – Don’t go to work without having breakfast.
Bakmadan geçme. – Don’t pass by without looking.

With -madan önce, you add another önce (before), so it literally becomes:

before before doing X, which is usually redundant.

You use -madan önce when the focus is strongly on the time sequence, rather than the idea of without doing X:

Almadan önce fiyatları karşılaştır. – Before you buy it (before taking it), compare prices.

In your sentence, the natural meaning is without your wallet, so plain almadan is the best choice.