block · fort

1. Origins, structure, and basic meaning

• Structure: 塞 expresses blocking or being blocked; its on-reading is さい.
• Basic usage: 塞ぐ(ふさぐ) describes blocking something, while 塞がる(ふさがる) describes something becoming blocked.

2. Common pitfalls and similar expressions

• What blocks and what is blocked
  • 木が山道を塞いでいた means that a tree was blocking the mountain road. The description centers on the tree doing the blocking.
  • 排水口が塞がって means with the drain blocked. 塞がる describes the condition of the blocked place, such as a drain or hole.