Definition

Adverb: - Extremely, exceedingly, very: Used to emphasize a high degree or intensity of a quality, state, or action. It often carries a colloquial or emphatic tone, similar to "terribly," "awfully," or "incredibly" in English.

Usage Examples

• Adverb:
  • Món ăn này ngon phải biết! (This dish is extremely delicious!)
  • Cô ấy giận phải biết khi nghe tin đó. (She was terribly angry when she heard that news.)
  • Hôm nay nóng phải biết. (It's incredibly hot today.)

Advanced Usage

• "phải biết" as an intensifier: This word is almost exclusively used in informal, spoken Vietnamese to add strong emphasis. It is typically placed after an adjective or a verb describing a state.
  • Sau chuyến đi dài, mệt phải biết. (After the long trip, [I] was awfully tired.)
  • Phen này hắn thua phải biết. (This time, he will lose for sure / badly.)

Variants and Related Words

• Cực kỳ: Extremely, exceedingly (more standard/formal than ).
• Vô cùng: Immensely, extremely (more literary or emphatic).
• Quá: Too, very (common and versatile intensifier).

Synonyms

• Rất: Very.
• Lắm: Very much (often used at the end of a sentence).
• Hết sức: Utterly, to the utmost.

Notes on Meaning

• The word "phải biết" is primarily used in Southern Vietnamese dialects and is considered informal. Its core function is to express a high degree, often with a sense of personal conviction or exclamation about the intensity of an experience.
• It should not be confused with the separate, literal phrase meaning "must know" (e.g., - "You must know that"). The intensifier is used as a fixed, inseparable unit.

1. mighty