悔しい

1. Origins, structure, and basic meaning

• Structure: 悔しい is read as くやしい and is an i-adjective for feeling frustrated, mortified, or aggrieved after an unwanted or unfair outcome.
• Basic usage: Expressing frustration after a one-point loss appears in 負けたのが悔しい, while expressing resentment at apologizing while misunderstood appears in 謝るのは悔しかった.

2. Common pitfalls and similar expressions

• Distinction from 悲しい
  • 悔しい expresses frustration or resentment after defeat or unfair treatment, whereas 悲しい focuses on sorrow from loss or misfortune.