1. unable to be sunk or made to go under water
Usage: nautical
2. unable to be defeated, destroyed, or overcome; indestructible
Usage: figurative

Examples

• The engineers claimed the new ship was unsinkable.
• The Titanic was famously called unsinkable before its tragic voyage.
• She has an unsinkable spirit that helps her overcome any challenge.
• His unsinkable optimism kept the team motivated during difficult times.
• The company’s unsinkable reputation survived the scandal.
• Despite the storm, the unsinkable boat remained afloat.