頑健

1. Origins, structure, and basic meaning

• Structure: 頑健（がんけん） describes a robust, sturdy body or physique.
• Basic usage: It modifies physique in 頑健な体つき or describes a person's physical robustness.

2. Common pitfalls and similar expressions

• Health versus a sturdy physique
  • 健康 broadly describes health, whereas 頑健 puts more emphasis on bodily strength and sturdiness.
• A shared character, a different focus
  • 頑固 focuses on being unwilling to change one's views or attitude. The shared character 頑 does not make physical robustness and temperament the same concept.