疲労

1. Origins, structure, and basic meaning

• Structure: 疲労 (ひろう) is a noun for physical or mental fatigue accumulated through sustained activity.
• Basic usage: 目に疲労がたまる locates fatigue accumulated through long work in the eyes, while 昨日の疲労が取れる describes partial recovery after sleep.

2. Common pitfalls and similar expressions

• Accumulation and recovery
  • 疲労がたまる increases accumulated burden, whereas 疲労が取れる reduces it. Because the second is qualified by 少し, it does not mean complete recovery.