Unsinkable (adjective)

Not able to sink; buoyant; able to float.

Origin:

Formed from the prefix un- meaning not, and sinkable meaning capable of sinking.

Examples:

1. The Titanic was thought to be unsinkable but it met its tragic end.
2. The life rafts are unsinkable and can support many people.
3. The unsinkable material can be used to make boats and ships more buoyant.
4. The unsinkable buoyancy of the ships help to prevent sinking.
5. The unsinkable buoyancy aid is designed to keep the wearer afloat in water.