الديل طويل.

A common Levantine pronunciation is id-deyl ṭwīl or ed-deyl ṭwīl.

A few notes:

• الديل is usually pronounced id-deyl / ed-deyl, not al-deyl
• طويل in everyday Levantine is often ṭwīl, while a more careful pronunciation may sound closer to ṭawīl

So the whole sentence sounds roughly like id-deyl ṭwīl.

Because د is a sun letter.

In Arabic, when ال comes before a sun letter, the l sound assimilates to the next consonant. So:

• الديل is written with ال but pronounced more like
• id-deyl or ed-deyl

The spelling stays the same, but the pronunciation changes.

In Arabic, especially in the present tense, you usually do not say a separate word for is.

So:

• الديل طويل literally looks like the-tail long but it means The tail is long

This is completely normal in both Levantine Arabic and Standard Arabic.

Arabic normally puts a descriptive adjective after the noun, not before it.

So:

• الديل الطويل = the long tail not the tail long

In your sentence, though, طويل is not part of the noun phrase the long tail. It is the predicate of the sentence:

• الديل طويل = The tail is long

So the order is:

• subject: الديل
• predicate: طويل

Because these two forms mean different things:

• الديل طويل = The tail is long
• الديل الطويل = the long tail

In الديل طويل, طويل is the predicate adjective, so it stays indefinite.

In الديل الطويل, طويل is directly describing the noun inside the same noun phrase, so it must match the noun in definiteness and take ال too.

Because ديل is a masculine singular noun, so the adjective must agree with it.

Arabic adjectives agree with the noun in:

• gender
• number
• definiteness

So here:

• الديل = masculine singular definite
• طويل = masculine singular

If the noun were feminine, you would use طويلة instead.

Yes. In Standard Arabic, the word is normally ذيل.

In many Levantine varieties, ذ is often pronounced as د in everyday speech, so learners commonly see or hear:

• Standard Arabic: ذيل
• Levantine everyday speech: ديل

So they are the same basic word, just in different registers or pronunciations.

It is very natural in Levantine, especially with ديل.

A Standard Arabic version would more typically be:

• الذيل طويل

The sentence structure itself works in both:

• the noun + adjective/predicate
• no present-tense is

What makes your sentence feel clearly Levantine is mainly the use of ديل instead of ذيل.

This is a nominal sentence.

That means it starts with a noun rather than a verb. In simple terms:

• الديل = the subject
• طويل = what is being said about it

So the pattern is:

• noun + description

This is one of the most common sentence types in Arabic.