Definition

1. Noun:
   • Theory: A system of ideas or a set of principles intended to explain something, especially one based on general principles independent of the specific thing to be explained. It is the abstract, conceptual part of a subject, often contrasted with practical application.
   • Theoretical knowledge / The theoretical side: Knowledge or study that concerns the understanding of principles and hypotheses rather than their practical application.

Usage Examples

• Noun:
  • Anh ấy nghiên cứu lí thuyết lượng tử. (He studies quantum theory.)
  • Chúng tôi đã học xong phần lí thuyết và bắt đầu thực hành. (We finished the theoretical part and started the practical work.)
  • Cần phải kết hợp nhuần nhuyễn giữa lí thuyết và thực tiễn. (It is necessary to seamlessly combine theory and practice.)

Advanced Usage

• "Lí thuyết suông" / "Lí thuyết viển vông": Empty theory / Impractical theory. Refers to theories that are abstract, not grounded, or have no practical value.

  • Kế hoạch đó chỉ là lí thuyết suông, không thể áp dụng. (That plan is just empty theory; it cannot be applied.)

• "Trên lí thuyết": In theory, theoretically. Used to describe a conclusion or statement that is logically deduced from principles but may not be true in reality.

  • Trên lí thuyết, phương án này là khả thi nhất. (In theory, this option is the most feasible.)

Variants and Related Words

• Lí luận (n): Reasoning, argumentation, discourse. Often refers to the logical framework or system of arguments behind a theory.

  • Bài viết có lí luận chặt chẽ. (The essay has tight reasoning.)

• Giả thuyết (n): Hypothesis. A proposed explanation made on the basis of limited evidence as a starting point for further investigation.

  • Nhà khoa học đưa ra một giả thuyết mới. (The scientist proposed a new hypothesis.)

Synonyms

• Theory: A supposition or a system of ideas.
• Doctrine: A belief or set of beliefs held and taught by a group.
• Principle: A fundamental truth or proposition serving as the foundation for belief or system.

Related Idioms

• "Nói lí thuyết": To speak theoretically. Can imply that someone is talking in abstract terms without practical understanding or experience.
  • Anh ta chỉ biết nói lí thuyết, chứ làm thì không được. (He only knows how to talk theory, but can't actually do the work.)