Buku harian saya sangat rahasia.

My diary is very secret.

Breakdown of Buku harian saya sangat rahasia.

• adalah: to be
• buku: the book
• sangat: very
• harian: daily
• rahasia: secret

Questions & Answers about Buku harian saya sangat rahasia.

What does each word in Buku harian saya sangat rahasia literally mean?

Word by word:

• buku = book
• harian = daily / of the day (from hari = day)
• buku harian together = diary
• saya = I / me; after a noun it means my
• sangat = very
• rahasia = secret / confidential

So the structure is roughly: “book-daily my very secret”, which corresponds to “My diary is very secret.”

Is buku harian a fixed expression for diary, or is it just buku + harian?

It’s both:

• Literally, buku harian = daily book.
• In practice, it’s a common, fairly standard way to say diary in Indonesian.

You may also sometimes see:

• diari – a direct borrowing of diary, a bit more formal / written
• jurnal – closer to journal / log, often used for work or study notes

For an everyday personal diary, buku harian is very natural and widely understood.

Why is saya placed after buku harian instead of before it, like in English?

In Indonesian, possessive pronouns (my, your, his, etc.) usually come after the noun:

• buku saya = my book
• rumah mereka = their house
• buku harian saya = my diary

Putting saya before the noun does not mean “my X”.
So:

• saya buku harian is wrong as “my diary”.
• The correct form is buku harian saya.

Can I replace saya with aku or -ku here? What difference does it make?

Yes, but the tone changes.

You have 3 common “my” options:

1. saya (neutral–polite, standard)

   • buku harian saya sangat rahasia
   • Sounds neutral, respectful, good in most situations.

2. aku (informal “I”)

   • As a possessive, you usually change it to -ku attached to the noun:
     
     • buku harianku sangat rahasia = my diary is very secret
   • This sounds more personal, informal, or literary.

3. gua/gue (very informal Jakarta slang)

   • buku harian gua rahasia banget (colloquial)

So:

• buku harian saya = neutral, safe in conversation or writing
• buku harianku = more intimate / informal or sometimes poetic
• Don’t say aku buku harian for “my diary”; use buku harianku.

Why is there no word for “is” in the Indonesian sentence?

Indonesian usually drops the verb “to be” when linking a subject to an adjective:

• Dia cantik. = She (is) beautiful.
• Makanan ini enak. = This food (is) delicious.
• Buku harian saya sangat rahasia. = My diary (is) very secret.

There is a linking word adalah, but it is mostly used:

• Before a noun/noun phrase:
  
  • Dia adalah dokter. = He is a doctor.
• Or in more formal / written contexts.

With a simple adjective like rahasia, you normally do not insert a word for “is”.

Can I say Buku harian saya adalah sangat rahasia? Is that correct?

It is grammatically possible, but it sounds:

• Very formal, or
• Slightly influenced by English, and a bit unnatural in everyday speech.

Natural options:

• Buku harian saya sangat rahasia. – best, neutral
• Buku harian saya benar‑benar rahasia. – really secret (slightly stronger emphasis)

If you do use adalah, it’s more natural before a noun phrase:

• Buku harian saya adalah dokumen yang sangat rahasia.
  = My diary is a very secret document.

What is the difference between sangat, sekali, and banget for “very”?

All three can intensify an adjective, but they differ in style and position:

1. sangat

   • Meaning: very
   • Position: before the adjective
     
     • sangat rahasia
   • Style: neutral, slightly formal; good in writing and speech.

2. sekali

   • Meaning: very / extremely
   • Position: after the adjective
     
     • rahasia sekali
   • Style: neutral, common in speech and writing.

3. banget

   • Meaning: really / so (very)
   • Position: after the adjective
     
     • rahasia banget
   • Style: informal, colloquial (especially Jakarta / urban speech).

So you could say:

• Buku harian saya sangat rahasia. (neutral)
• Buku harian saya rahasia sekali. (neutral)
• Buku harian saya rahasia banget. (very informal / casual)

Is rahasia used as both a noun and an adjective?

Yes, rahasia can function as:

1. A noun = “a secret”

   • Itu rahasia. = That’s a secret.
   • Saya punya rahasia. = I have a secret.

2. An adjective = “secret / confidential / private”

   • informasi rahasia = secret information
   • dokumen rahasia = confidential documents
   • buku harian saya sangat rahasia = my diary is very secret/private

Context and surrounding words tell you whether it’s acting more like a noun or an adjective.

How would I say “My diaries are very secret” (plural) in Indonesian?

Indonesian plural marking is flexible. You have two main options:

1. Rely on context (most common):

   • Buku harian saya sangat rahasia.
     This can mean “my diary is very secret” or “my diaries are very secret” depending on context.

2. Explicit plural with reduplication:

   • Buku‑buku harian saya sangat rahasia.
     This more clearly suggests multiple books.

Often, people still just say buku harian saya and let context show whether it’s one diary or several.

Are there other natural ways Indonesians might express the same idea?

Yes, depending on nuance:

• Buku harian saya sangat pribadi.
  = My diary is very personal/private.

• Buku harian saya sangat pribadi dan rahasia.
  = My diary is very personal and secret.

• Jangan baca buku harian saya, itu sangat rahasia.
  = Don’t read my diary, it’s very secret.

• In casual speech:

  • Diary gue rahasia banget.
  • Buku harian aku rahasia banget.

Your original sentence Buku harian saya sangat rahasia. is already natural and correct; these are just stylistic variations.