堅固

1. Origins, structure, and basic meaning

• Structure: The spelling is 堅固, read けんご, and it combines 堅, meaning hard or firm, with 固, meaning solid or fixed. It functions as a noun or na-adjective.
• Basic usage: The basic sense of 堅固 is physical sturdiness that resists collapse or abstract firmness that makes a relationship or foundation hard to shake.

2. Common pitfalls and similar expressions

• Physical solidity and figurative firmness
  • Both examples use the form 堅固. It describes structural strength in a castle wall and firmly established stability in a relationship of trust.
• A stone wall and trust built over many years
  • 石造りの城壁は非常に堅固でした。 — The stone castle wall was extremely solid.
  • 二人は長年かけて堅固な信頼関係を築きました。 — Over many years, the two built a firm relationship of trust.