必死

1. Origins, structure, and basic meaning

• Structure: 必死 (ひっし) literally joins inevitability 必 and death 死, but in current use it marks desperate, all-out effort.
• Basic usage: It describes someone struggling with all available strength in an urgent situation.

2. Common pitfalls and similar expressions

• Adverbial に and attributive の
  • 必死に modifies an action as desperate, while 必死の modifies a noun such as an expression or effort.