rất

Rất is a common way to say "very" in Vietnamese. While it is used in everyday conversation, it leans slightly formal and is very common in writing. In casual speech (especially in the South), native speakers often prefer words like lắm or quá to add warmth.

1. What it attaches to:

• Adjectives: rất nóng (very hot), rất tốt (very good).
• Adverbs: chạy rất nhanh (run very fast), nói tiếng Việt rất giỏi (speak Vietnamese very well).
• Verbs of emotion or thought: rất thích (really like), rất nhớ (really miss), rất hiểu (understand very well).
• Not for action verbs: You cannot use rất directly with regular action verbs (e.g., you cannot say rất ăn or rất đi). To say you do an action a lot, use nhiều instead (e.g., ăn rất nhiều = eat a lot).

2. Position:
It strictly goes before the word it modifies. This is an important difference from other intensifiers like lắm and quá, which usually go after the adjective (note that quá can also go before the adjective to mean "too" or "excessively", as in quá nóng).

3. Cannot stand alone:
Unlike English where you can answer a question with just "Very", in Vietnamese you must include the adjective. For example, to say you are very tired, you must say Rất mệt, not just Rất.

4. Conversational "rất là":
In casual speech, you will frequently hear rất là instead of just rất (e.g., rất là ngon = very delicious). Adding là makes the phrase sound less stiff and more natural in conversation.

Important Note: While a bare adjective is grammatically fine as a predicate (e.g., Cô ấy đẹp = She is beautiful), native speakers often use intensifiers to make simple statements sound more natural and complete. However, overusing rất in casual speech can sound a bit stiff; try mixing in lắm, quá, or using rất là to sound more conversational.