壮年

1. Origins, structure, and basic meaning

• Structure: In 壮年 (そうねん), vigorous 壮 and years 年 combine to denote prime adulthood.
• Basic usage: 壮年 denotes the vigorous period of mature or middle adulthood.

2. Common pitfalls and similar expressions

• Prime adulthood without a fixed cutoff
  • The word alone does not fix exact starting and ending ages, so the context's age convention governs.