حقيبة الظهر كبيرة وجاهزة.

This is because حقيبة الظهر is an iḍāfa construction, often called a construct phrase.

• حقيبة = bag
• الظهر = the back

Together, they literally mean the bag of the back, which is the normal Arabic way to say backpack.

In an iḍāfa:

• the first noun usually does not take الـ
• the whole phrase becomes definite if the second noun is definite

So:

• حقيبة ظهر = a backpack / back bag
• حقيبة الظهر = the backpack

That is why the whole phrase is definite, even though the first word does not have الـ.

Because this expression is built as حقيبة الظهر = backpack.

The second noun in an iḍāfa often identifies what kind of thing the first noun is. Here:

• حقيبة = bag
• الظهر = the back

So the phrase means the bag associated with the back. In Arabic, this is the natural structure for many compound-like expressions.

Also, because الظهر is definite, the whole phrase becomes definite: the backpack.

They are feminine because حقيبة is a feminine noun.

In Arabic, adjectives and predicate adjectives must agree with the noun in:

• gender
• number
• usually definiteness when they directly describe a noun

Here, حقيبة الظهر is the subject, and its head noun is حقيبة, which is feminine singular. So the predicates are also feminine singular:

• كبيرة = big
• جاهزة = ready

The ـة ending is a common sign of the feminine form.

In Arabic, the present tense usually does not use a separate word for is / am / are.

So:

• حقيبة الظهر كبيرة literally looks like the backpack big
• but it means the backpack is big

This is completely normal in Arabic nominal sentences.

If you wanted the past tense, you would use كان:

• كانت حقيبة الظهر كبيرة وجاهزة = The backpack was big and ready

They are predicates of the sentence.

The structure is:

• حقيبة الظهر = subject / topic
• كبيرة وجاهزة = predicate

So the sentence is a basic nominal sentence:

• حقيبة الظهر = the backpack
• كبيرة وجاهزة = big and ready

Together: The backpack is big and ready.

Because here they are not attributive adjectives directly attached to the noun. They are predicate adjectives.

Compare these two patterns:

1. Attributive adjective

   • حقيبة الظهر الكبيرة
   • the big backpack
     Here, الكبيرة must match the noun phrase in definiteness.

2. Predicate adjective

   • حقيبة الظهر كبيرة
   • The backpack is big
     Here, كبيرة is part of the predicate, so it is usually indefinite in form.

That is why كبيرة and جاهزة do not take الـ here.

A fully vowelled version would be:

حَقِيبَةُ الظَّهْرِ كَبِيرَةٌ وَجَاهِزَةٌ

Breakdown:

• حَقِيبَةُ: nominative, because it is the subject
• الظَّهْرِ: genitive, because it is the second term of an iḍāfa
• كَبِيرَةٌ: nominative predicate
• وَجَاهِزَةٌ: second nominative predicate

In normal everyday writing, these short vowels are usually omitted.

In الظهر, the ل of الـ is not pronounced clearly because ظ is a sun letter.

So:

• written: الظهر
• pronounced: approximately aẓ-ẓahr

This doubling of the first consonant is normal with sun letters.

So the whole phrase is pronounced roughly: ḥaqībat aẓ-ẓahr kabīrah wa jāhizah

The word itself does not change because it is before another noun; it changes because of case endings.

In an iḍāfa, the first noun takes whatever case the sentence requires:

• حقيبةُ الظهر if nominative
• حقيبةَ الظهر if accusative
• حقيبةِ الظهر if genitive

In this sentence, it is the subject, so it is nominative:

• حقيبةُ الظهر

So the important point is:

• being in iḍāfa affects definiteness and prevents tanwīn
• the actual ending still depends on grammar

Because nouns in an iḍāfa construction do not take tanwīn on the first noun.

Normally, an indefinite noun might have tanwīn:

• حقيبةٌ = a bag

But in iḍāfa:

• حقيبةُ الظهر = the backpack

The first noun:

• does not take الـ
• does not take tanwīn

That is one of the main signs that a noun is the first part of an iḍāfa.

Not naturally in this exact form.

Because حقيبة الظهر is definite, the normal meaning is:

• The backpack is big and ready

If you wanted a backpack, you would usually make the phrase indefinite, for example:

• حقيبةُ ظهرٍ كبيرةٌ وجاهزةٌ or a more natural indefinite phrasing depending on context

So the sentence as given is best understood as referring to a specific backpack: the backpack.

جاهزة means ready.

In this sentence, it means the backpack is prepared or set for use. Depending on context, it could suggest:

• packed and ready
• available
• prepared

Because it matches حقيبة, it appears in the feminine singular form:

• masculine: جاهز
• feminine: جاهزة

Yes. You could say:

حقيبة الظهر جاهزة وكبيرة

This would still mean: The backpack is ready and big

The meaning is very similar, but the first adjective often gets slightly more emphasis. So:

• كبيرة وجاهزة may foreground size first
• جاهزة وكبيرة may foreground readiness first

Both are grammatically correct.

حقيبة الظهر is a fixed noun phrase meaning backpack.

It is not the same as a phrase that literally describes a bag located on the back.

For example:

• حقيبة الظهر = backpack
• a phrase like الحقيبة على الظهر would mean the bag is on the back

So in your sentence, الظهر is not telling you where the bag currently is. It is part of the noun expression backpack.

You could analyze it like this:

• حقيبةُ الظهرِ = mubtadaʾ (subject/topic), an iḍāfa phrase
• كبيرةٌ وجاهزةٌ = khabar (predicate), made of two coordinated adjectives

So it is a standard Arabic nominal sentence with:

• one subject phrase
• two coordinated predicate adjectives linked by و = and

That is why the sentence is simple but very useful for learning several core patterns at once.