كلما فتشنا حجرة مخفية، ازداد الخوف.

كلما means something like whenever, every time, or the more ... the more ... depending on context.

In this sentence, it introduces a repeated relationship:

• كلما فتشنا حجرة مخفية = Whenever we searched a hidden room
• ازداد الخوف = the fear increased

So the structure is:

• كلما + clause 1, clause 2

It often describes something that happens repeatedly, with the second clause following from the first each time.

This is very normal in Arabic.

After كلما, Arabic commonly uses the perfect/past tense to describe actions that happen repeatedly whenever a certain situation occurs. English often uses the present in similar general statements, but Arabic can use the past here without meaning only one past event.

So:

• فتشنا literally looks like we searched
• ازداد literally looks like increased

But in this structure, they can express a repeated pattern:

• Whenever we searched ..., fear increased.

This is one of those places where Arabic tense usage does not match English tense usage exactly.

فتشنا is a past-tense verb meaning we searched or we inspected.

It comes from the root ف-ت-ش and the dictionary form is فتّشَ.

Breakdown:

• فتّشَ = he searched / inspected
• فتّشنا = we searched / inspected

The ending -نا is the subject marker for we.

So the subject we is already built into the verb; Arabic does not need a separate pronoun here.

Because Arabic verbs already show the subject.

In فتشنا, the ending -نا tells you the subject is we. So Arabic usually does not add نحن unless there is a special reason, such as emphasis or contrast.

Compare:

• فتشنا = we searched
• نحن فتشنا = we searched (with extra emphasis, something like we were the ones who searched)

In ordinary sentences, the verb alone is enough.

حجرة means a room / a chamber here, and it is:

• singular
• indefinite (not the room, but a room)

Arabic often uses the singular indefinite noun naturally in this kind of statement. It does not need to match an English plural if the idea is generic.

So:

• حجرة = a room / a chamber
• not الحجرة = the room

The sentence is talking about any hidden room that gets searched each time, not one specific previously identified room.

Because it is describing حجرة, and adjectives in Arabic agree with the noun they describe.

حجرة is:

• feminine
• singular
• indefinite

So the adjective must match that:

• مخفية = hidden, feminine singular indefinite

This is normal adjective agreement in Arabic.

So:

• حجرة مخفية = a hidden room

If the noun were masculine, the adjective would be masculine too.

ازداد is a past-tense verb meaning increased, grew, or became greater.

It comes from the root ز-ي-د / ز-ا-د, related to increase. The verb here is a derived form that often has the sense of becoming more.

So:

• ازداد الخوف = the fear increased / fear grew

It is an intransitive verb here, meaning the fear itself became stronger.

Because the subject is الخوف, and الخوف is masculine singular.

In the clause:

• ازداد الخوف

the verb comes before the subject. The verb is therefore singular, and its gender matches the subject:

• ازداد = masculine singular
• الخوف = masculine singular

If the subject were a feminine singular noun, you would expect ازدادت.

الخوف means the fear. The definite article can be used here for a few related reasons:

• it can refer to the fear already understood in the situation
• it can express fear as a known, present phenomenon in the story
• Arabic often uses a definite noun where English might say simply fear

So ازداد الخوف is very natural Arabic for:

• fear increased
• the fear increased

Depending on context, English may or may not keep the.

A fully vocalized version would typically be:

كُلَّما فَتَّشْنا حُجْرَةً مَخْفِيَّةً، ازْدادَ الخَوْفُ.

The endings are:

• حُجْرَةً → accusative, because it is the direct object of فتشنا
• مَخْفِيَّةً → accusative too, because it is the adjective describing حجرة
• الخَوْفُ → nominative, because it is the subject of ازداد

In normal unvocalized writing, these case endings are usually not written.

They are similar, but not always identical.

• غرفة is the more common everyday word for room
• حجرة can also mean room, chamber, or sometimes a more enclosed/specific room

In many contexts they overlap, but حجرة can sound a little more literary or formal depending on the sentence.

So in this sentence, حجرة مخفية gives a slightly atmospheric sense: a hidden chamber/room.

The sentence has two parts:

1. كلما فتشنا حجرة مخفية
   = a subordinate clause introduced by كلما

2. ازداد الخوف
   = the main result clause

So the pattern is:

• Whenever X happened, Y increased

This is a very useful Arabic structure for repeated cause-and-effect or repeated correlation.