Thân cây khá lớn.

Thân cây is a noun phrase meaning tree trunk or plant stem, depending on context.

• thân = body, trunk, stem
• cây = tree, plant

Vietnamese often combines nouns this way, where the first noun names the part and the second noun tells what it belongs to. So thân cây is literally something like the body/stem of the plant/tree.

In natural English, you would usually translate it as:

• the trunk (for a tree)
• the stem (for a smaller plant)

So this is a very normal Vietnamese structure.

Vietnamese often leaves out to be when describing something with an adjective.

So:

• Thân cây khá lớn.
• literally: Tree trunk quite big.
• natural English: The trunk is quite big.

This is completely normal in Vietnamese. When an adjective works as the main predicate, you usually do not need là.

For example:

• Cây cao. = The tree is tall.
• Nhà đẹp. = The house is beautiful.

Using là here would usually sound unnatural or incorrect in ordinary descriptive sentences.

Khá means quite, rather, or fairly.

It shows a moderate degree, stronger than just saying the trunk is big, but not as strong as something like very.

So:

• lớn = big
• khá lớn = quite big / fairly big / rather big

It often has a slightly neutral or mildly positive feel, depending on context.

Compare:

• Thân cây lớn. = The trunk is big.
• Thân cây khá lớn. = The trunk is quite big.
• Thân cây rất lớn. = The trunk is very big.

In this sentence, lớn is not directly modifying the noun inside a noun phrase. It is the main descriptive part of the sentence.

Structure:

• Thân cây = subject/topic
• khá lớn = predicate description

So the pattern is basically:

noun phrase + degree word + adjective

This is very common in Vietnamese:

• Con chó rất nhỏ. = The dog is very small.
• Căn phòng khá rộng. = The room is quite spacious.

So lớn comes after thân cây because it is part of the statement being made about the trunk.

No, not in this sentence.

Lớn usually means big, large, or sometimes grown up depending on context.

Examples:

• nhà lớn = big house
• đứa bé đã lớn = the child has grown up

With thân cây, lớn clearly refers to physical size, so it means big/large.

If you wanted to say a tree is old, you would use words like:

• già = old

For example:

• Cây này già. = This tree is old.

Yes, often you can, but there is a slight nuance.

Both to and lớn can mean big.

• to often emphasizes physical bulk or width
• lớn is more general and very common

So:

• Thân cây khá lớn.
• Thân cây khá to.

Both can work for The trunk is quite big.

In many everyday contexts, they are close in meaning. But lớn is often the safer, more general choice for learners.

Not always. It can also mean plant stem, depending on what kind of cây you are talking about.

For example:

• for a large tree, thân cây is usually the trunk
• for a smaller plant or flower, thân cây may be the stem

So the exact English translation depends on context.

That said, if a learner sees Thân cây khá lớn, the most likely image is a tree trunk, because quite big fits a trunk more naturally than a small stem.

Vietnamese does not use articles the same way English does.

So Thân cây khá lớn does not explicitly say:

• a trunk
• the trunk

The exact English choice depends on context.

Possible translations:

• The trunk is quite big.
• This tree’s trunk is quite big.
• A tree trunk is quite big. (less likely in isolation)

In most contexts, English would naturally use the trunk because Vietnamese often leaves definiteness unstated.

A simple pronunciation guide is:

• thân — roughly like tuhn with a short neutral-level tone
• cây — roughly like guy/kuh-ee blended, with a falling tone
• khá — kha with a rising tone
• lớn — roughly lurn with a rising tone

A few helpful points:

• th in Vietnamese is an aspirated t, not the English th sound
• kh is like a strong breathy k, somewhat similar to the ch in German Bach or Scottish loch
• â in thân is a short central vowel
• ơ in lớn is a vowel English does not have exactly, so it may take practice

Tones matter a lot in Vietnamese, so it is good to learn the sentence together with its tones:

• thân = level
• cây = falling
• khá = rising
• lớn = rising

You can change the degree word.

• Thân cây rất lớn. = The trunk is very big.
• Thân cây không lớn lắm. = The trunk is not very big.
• Thân cây không quá lớn. = The trunk is not too big.
• Thân cây hơi lớn. = The trunk is a bit big.

This is a useful pattern:

• [noun phrase] + [degree word] + adjective
• [noun phrase] + không + adjective + lắm

So once you understand Thân cây khá lớn, you can build many similar sentences easily.