Vietnamese property words can be expanded by whole clauses: someone can be happy because a friend came, certain that a train has left, or so tired that they fall asleep. The crucial point is that the property word remains a predicate. It does not need an equivalent of English be, and the following clause supplies a cause, content, consequence, standard, or degree.
This page is about clauses that complete or elaborate a property expression. It is not about fixed lexical combinations such as áo dài or cá vàng; those belong on Noun–Adjective Compounds.
Start from the stative-predicate pattern
Many Vietnamese words translated as English adjectives behave like stative verbs. They can follow the subject directly and take degree words or aspect markers:
Căn nhà đẹp.
The house is beautiful.
Căn nhà rất đẹp.
The house is very beautiful.
Căn nhà đẹp lắm.
The house is really beautiful.
Căn nhà này đẹp hơn.
This house is more beautiful.
The same syntax remains in place when a clause follows the property word:
Tôi vui vì bạn đã đến.
I am happy because you came.
There is no là before vui. The phrase vì bạn đã đến explains the cause of the state. English requires am because happy cannot normally head a finite predicate alone; Vietnamese does not.
Cause clauses: vì and related connectors
With emotions and evaluations, vì + clause gives the reason for the property. It answers “why?” and is not an object in the same sense as the content after chắc “certain.”
Lan buồn vì không kịp chào bà.
Lan is sad because she did not get to say goodbye to her grandmother.
Tôi hơi lo vì sáng nay anh ấy chưa gọi lại.
I am a little worried because he has not called back this morning.
Cả nhóm rất tự hào vì dự án đã được chọn.
The whole team is very proud because the project was selected.
In everyday speech, the reason can also be presented as a separate following sentence. Keeping vì makes the dependency explicit. (formal) writing may use do or bởi vì, but ordinary conversation strongly favors vì in this pattern.
Content clauses after certainty and evaluation
Some property predicates are incomplete unless the listener can recover what is certain, obvious, possible, or important. A following clause supplies that content. Rằng explicitly introduces the proposition, especially in careful writing, but it is often omitted in speech after predicates such as chắc.
Tôi chắc rằng cửa hàng vẫn mở.
I am sure that the shop is still open.
Tôi chắc anh ấy sẽ hiểu.
I am sure he will understand.
Điều quan trọng là mọi người đều an toàn.
The important thing is that everyone is safe.
The last example contains là, but its job is not to prop up an adjective. Là links the nominal expression điều quan trọng “the important thing” to an identifying content clause. Compare the direct property predicate:
Mọi người đều an toàn mới quan trọng.
What matters is that everyone is safe.
With a direct predicate such as chắc, adding là before the property is normally wrong: Tôi là chắc... does not mean “I am sure.”
Aspect and reduplication remain inside the predicate
Because the property expression is a predicate, a time-aspect particle can locate the state before its following clause without changing the property word itself:
Tôi đã rất lo vì anh ấy chưa gọi lại.
I was very worried because he had not called back.
Likewise, a reduplicated property can take a following consequence clause:
Trời lành lạnh nên mọi người ngồi sát lại bên bếp lửa.
It was a little chilly, so everyone sat closer together by the fire.
The reduplicative lành lạnh softens the degree of coldness; nên then introduces its consequence. Lexical boundaries still matter. In chiếc áo dài đẹp đến mức ai cũng ngoái nhìn “the áo dài so beautiful that everyone turns to look,” áo dài is the garment name, while đẹp đến mức... evaluates that garment. The following clause does not modify the lexicalized syllable dài “long” inside áo dài.
Result and degree clauses
A clause can identify the consequence that proves the degree of a property. Several frames are common:
| Frame | Core meaning | Typical use |
|---|---|---|
| adjective + đến mức + clause | so … that | explicit degree-result relation |
| quá + adjective + nên + clause | so/too …, therefore | strong degree followed by result |
| adjective + đến nỗi + clause | so … that | often striking or undesirable result |
| đủ + adjective + để + clause | … enough to | reaching a threshold |
Bài báo khó đến mức tôi phải đọc ba lần.
The article was so difficult that I had to read it three times.
Anh ấy quá mệt nên ngủ quên trên xe buýt.
He was so tired that he fell asleep on the bus.
Phòng đủ rộng để cả nhóm ngồi họp.
The room is large enough for the whole group to meet in.
Here đến mức and đến nỗi introduce a result that measures the degree. By contrast, vì introduces a cause. Replacing one with the other reverses the logical direction: the cause produces the state, while the state reaches a degree that produces the result.
Inside a noun phrase
An expanded property predicate can modify a noun after that noun. The whole unit follows the head, just as a simple adjective does:
Họ đang tìm một căn nhà đủ rộng để mở lớp học.
They are looking for a house large enough to hold classes in.
Đó là một quyết định quan trọng đến mức ai cũng muốn phát biểu.
That is a decision so important that everyone wants to comment.
The simple modifier in căn nhà nhỏ màu xanh “the small green house” contains no following clause. In căn nhà đủ rộng để mở lớp học, however, đủ sets a threshold for rộng, and để mở lớp học states what that threshold makes possible. The order is still head noun first, property expression afterward. Although adjective + đủ để occurs in some contexts, đủ + adjective + để is the safest neutral pattern for learners.
Do not confuse a property’s complement with a relative clause that independently modifies the noun. In người vui vì được gặp lại bạn “the person happy to see you again,” vì được gặp lại bạn explains vui. In người mà bạn gặp hôm qua “the person whom you met yesterday,” the clause identifies người directly.
Degree words are not interchangeable
The following contrasts are small but important:
| Form | Meaning and position |
|---|---|
| rất đẹp | very beautiful; neutral preverbal degree |
| đẹp lắm | really/very beautiful; postposed and often more conversational |
| đẹp quá | so beautiful; often an exclamation in speech |
| quá đẹp nên… | so beautiful that/as a result… |
| hơi đẹp | somewhat beautiful; possible but pragmatically marked because hơi often softens less desirable properties |
Khách sạn mới đẹp lắm, nhưng hơi xa trung tâm.
The new hotel is really beautiful, but it is a little far from the center.
Quán nhỏ quá nên cuối tuần thường hết chỗ.
The café is so small that it is usually full on weekends.
In the first sentence, lắm closes the evaluation đẹp lắm before a contrasting clause begins. In the second, quá ... nên packages degree and consequence together.
A short dialogue: changing the interpretation
— Căn nhà nhỏ màu xanh thế nào? — Đẹp lắm, nhưng cũ đến mức phải thay cả mái.
— What is the small green house like? — It is very beautiful, but so old that the entire roof has to be replaced.
Here nhỏ and màu xanh identify the house. Đẹp lắm makes a stand-alone evaluation. The clause after cũ đến mức does more than add another fact: replacing the roof provides the scale by which the speaker judges the house “so old.” Without that result clause, cũ would merely report a property.
Common Mistakes
1. Copying English adjective order.
❌ Họ cần một đủ rộng để mở lớp học căn nhà.
Incorrect — the expanded property modifier has been placed before the noun.
✅ Họ cần một căn nhà đủ rộng để mở lớp học.
They need a house large enough to hold classes in.
The noun phrase begins with một căn nhà; the property and its threshold clause follow it.
2. Inserting là before an ordinary property predicate.
❌ Tôi là rất vui vì bạn đã đến.
Incorrect — là is not needed before the stative predicate vui.
✅ Tôi rất vui vì bạn đã đến.
I am very happy because you came.
3. Treating rất and lắm as if they occupied the same slot.
❌ Căn nhà lắm đẹp.
Incorrect — lắm does not normally precede the property word in this construction.
✅ Căn nhà rất đẹp. / Căn nhà đẹp lắm.
The house is very beautiful.
4. Confusing cause with result.
❌ Tôi vui đến mức bạn đã đến.
Incorrect for the intended meaning — đến mức presents what follows as a degree-result, not the cause of happiness.
✅ Tôi vui vì bạn đã đến.
I am happy because you came.
The repair works because vì explicitly marks the following event as the cause of the emotional state.
Key Takeaways
Vietnamese property words can predicate directly, take degree words, and then be expanded by clauses. Use vì for cause, rằng or a zero connector for propositional content, and frames such as đến mức, đến nỗi, quá ... nên, and đủ để for degree and result. When the expanded property modifies a noun, keep the noun first and the complete property expression after it.
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