頑強

1. Origins, structure, and basic meaning

• Structure: 頑強, read がんきょう, describes physical sturdiness or a stubbornly firm attitude.
• Basic usage: It describes sturdy metal parts reinforcing a box or resistance that does not yield to opposition.
  • この箱は頑強な金具で補強されている。

2. Common pitfalls and similar expressions

• The roles of な and に
  • な in 頑強な金具 forms a modifier for the following noun.
  • に in 頑強に抵抗した describes how the resistance was carried out.