Definition

1. Noun:
   • Main river / Principal river: The primary and largest river in a river system, often the one into which tributaries flow.
   • River (discharging into the sea): Specifically, a large river that flows directly into the sea or ocean. This is the most precise and common technical meaning.

Usage Examples

• Noun:
  • Sông Hồng và sông Thái Bình là hai sông cái quan trọng ở miền Bắc Việt Nam. (The Red River and the Thai Binh River are two important main rivers in Northern Vietnam.)
  • Sông Mekong là một sông cái lớn đổ ra Biển Đông. (The Mekong River is a large river discharging into the East Sea.)

Advanced Usage

• In geography and hydrology, "sông cái" is the direct Vietnamese equivalent of the term "fleuve" in French, distinguishing it from "sông" (a general river, which can be a tributary) or "rivière" (a river that flows into another river).

Variants and Related Words

• Sông (n): A general term for river or stream.
  • Nhiều sông nhỏ là phụ lưu của sông cái. (Many small rivers are tributaries of the main river.)
• Phụ lưu (n): Tributary (a river or stream flowing into a larger river).
• Chi lưu (n): Distributary (a branch of a river that flows away from the main stream).

Synonyms

• Main river
• Principal river
• Major river (flowing to the sea)

Related Concepts

• The concept contrasts with "sông nhánh" (branch river/tributary). A "sông cái" forms the main trunk of a river basin's drainage system.
• In some regional contexts, it can colloquially refer to the largest river in a local area, even if it does not reach the sea.

1. River (discharging into the sea)