الكباية بلاستيك.

A good Egyptian Arabic approximation is el-kobbāya balastīk.

A few notes:

• الـ is usually pronounced el- or il- in Egyptian, not al-.
• كباية is commonly pronounced something like kobbāya.
• بلاستيك is often pronounced balastik/balastīk in Egyptian speech.

So the whole sentence sounds roughly like el-kobbāya balastīk.

Because in Arabic, especially in the present tense, sentences like The cup is plastic usually do not use a separate word for is.

So:

• الكباية = the cup
• بلاستيك = plastic
• together: The cup is plastic

This is a very common Arabic pattern, often called a nominal sentence.

Because الكباية is the thing being talked about: the cup.
بلاستيك is the information being given about it: plastic.

In this kind of sentence:

• the first part is often definite
• the second part is often indefinite or unmarked

So الكباية بلاستيك means The cup is plastic, not the plastic cup.

As written, it means The cup is plastic.

That is because the sentence is set up as:

• الكباية = subject/topic
• بلاستيك = predicate/description

If you wanted a plastic cup, Egyptian Arabic can say كباية بلاستيك.

If you wanted the plastic cup, speakers may use a clearer phrasing such as الكباية البلاستيكية or another context-dependent structure.

كباية in Egyptian Arabic usually means a cup, glass, or drinking cup/container, depending on context.

So it does not always match one single English word perfectly. In everyday speech, it can refer to:

• a glass for water or juice
• a cup
• sometimes a disposable drinking container

The exact English translation depends on the situation.

Because dialect spelling is often flexible.

In Egyptian Arabic, the word may be written as:

• كباية
• كوباية

They refer to the same everyday word. In informal writing, people often spell Egyptian words in slightly different ways because there is less strict standardization than in Modern Standard Arabic.

Because Arabic traditionally does not have the p sound as a native consonant. So in many borrowed words, p becomes ب (b).

That is why plastic becomes بلاستيك.

Also, Arabic does not like some word beginnings that English allows, so the pronunciation often becomes something like balastik rather than plastik.

In this sentence, بلاستيك works like a material description: made of plastic / plastic.

In Egyptian Arabic, words like this are often used in a simple, fixed form, so they do not always show regular adjective agreement.

That is why you can say:

• الكباية بلاستيك = The cup is plastic

even though الكباية is feminine.

If you used a more fully adjective-like form, you might see something like بلاستيكية, which does show feminine marking.

Not exactly.

In Modern Standard Arabic, a more typical way to say this would be something like:

• الكوب من البلاستيك = The cup is made of plastic
• or الكوب بلاستيكيّ

In Egyptian Arabic:

• الكباية is the everyday dialect word
• بلاستيك is a very natural colloquial way to describe the material

So الكباية بلاستيك sounds Egyptian and everyday.