Buku itu tebal.

That book is thick.

Breakdown of Buku itu tebal.

• adalah: to be
• buku: the book
• itu: that
• tebal: thick

Questions & Answers about Buku itu tebal.

Why isn’t there a word for “is” in Buku itu tebal?

Indonesian often uses a zero–copula in simple descriptive sentences. You don’t need a separate verb “to be.” So Buku itu tebal literally reads “Book that thick,” but means “That book is thick.” In formal contexts you could insert adalah, but it’s rare before adjectives.

Why does itu come after buku? Could I say itu buku?

Demonstratives in Indonesian—ini (this) and itu (that)—always follow the noun they modify. So you must say buku itu (“that book”). Itu buku would sound awkward or wrong.

What if I want to say “this book is thick”?

Simply swap itu with ini:
Buku ini tebal.
(“This book is thick.”)

How do I make it plural: “the books are thick”?

Indonesian indicates plurality by context or by repeating the noun. You can say:
• Buku-buku itu tebal. (“Those books are thick.”)
• Or even just Buku itu tebal if it’s clear you mean several books.

Why is tebal placed at the end of the sentence?

In Indonesian, adjectives follow the noun (and its demonstrative). The order is:
noun → demonstrative → adjective.
So you get buku → itu → tebal.

Does tebal change for gender or number?

No. Indonesian adjectives are invariable. Tebal stays the same regardless of singular/plural or masculine/feminine subjects.

How can I say “That book is very thick”?

Add an intensifier like sangat (very) or colloquial banget:
• Buku itu sangat tebal.
• Buku itu tebal banget.

How would I turn it into a question: “Is that book thick?”

You have two common options:

1. Add the question marker apakah:
   Apakah buku itu tebal?
2. Use rising intonation only:
   Buku itu tebal?