Definition

1. Conjunction:
   • Once, when, as soon as: Used to indicate a condition or a point in time from which a certain consequence logically follows or an action begins. It expresses that if/when a particular condition is met or situation occurs, then something else will happen or be true.

Usage Examples

• Conjunction:
  • Một khi đã hứa thì phải giữ lời. (Once you have promised, you must keep your word.)
  • Một khi cô ấy đã quyết định, không ai có thể thay đổi. (Once she has decided, no one can change it.)
  • Một khi bạn hiểu nguyên tắc này, mọi thứ sẽ trở nên dễ dàng. (Once you understand this principle, everything will become easy.)

Advanced Usage

• "một khi mà...": This is a more emphatic or formal variant, often used in writing. The word "mà" adds a slight emphasis but does not change the core meaning.
  • Một khi mà lòng tin đã mất, rất khó để lấy lại. (Once trust is lost, it is very difficult to regain.)

Variants and Related Words

• Khi: A more general word for "when". "Một khi" is stronger, implying "once (a condition is met)" rather than just "at the time that".
• Hễ, hễ mà: Synonyms meaning "whenever" or "if", often used in conditional statements similar to "một khi", but can imply a more frequent or general condition.
  • Hễ trời mưa là đường lại ngập. (Whenever it rains, the road floods.)

Synonyms

• Một lần đã: A less common, more literary synonym for "once (something has happened)".
• Khi đã: A simpler construction meaning "when (something) has already...". It is close in meaning but "một khi" often carries a stronger sense of an inevitable consequence.

Related Phrases

• Một khi đã... thì...: This is the most common correlative structure. "Thì" (then) is often used in the second clause to emphasize the consequence.
  • Một khi đã bắt đầu thì phải làm cho xong. (Once you have started, you must finish it.)

Related Idioms

• Một khi bước chân vào...: Literally "once you step into...". Used to indicate that after entering a certain situation or field, certain rules or consequences apply.
  • Một khi bước chân vào giới kinh doanh, bạn phải chấp nhận cạnh tranh. (Once you step into the business world, you must accept competition.)

1. Once