堅牢

1. Origins, structure, and basic meaning

• Structure: 堅牢 is read けんろう and behaves as a na-adjective describing a structure or object as solid and sturdy.
• Basic usage: Use 門は堅牢だ predicatively and 堅牢な箱 before a noun.

2. Common pitfalls and similar expressions

• Na-adjective pattern
  • The form is 堅牢な before a noun and 堅牢だ at the end of a statement. Do not inflect it as an i-adjective such as 堅牢い.
• 堅牢 and 丈夫
  • 丈夫(じょうぶ) broadly describes durable objects and healthy people. 堅牢 is relatively formal and focuses on the solidity of buildings, containers, and structures.
• Not absolute indestructibility
  • It evaluates something as strong enough to endure; it does not guarantee that no force could ever damage it.