The quality of being quiet and secret to avoid being noticed.
Stealthinesses are often used by spies and ninjas to move without being seen or heard.
Examples:
The cat's stealthinesses allowed it to sneak up on the bird.
The spy moved with great stealthinesses to avoid detection.
His stealthinesses surprised everyone when he won the game.
The ninja's stealthinesses were so good, no one saw him coming.
The stealthinesses of the tiger are legendary in the jungle.
The stealthinesses of the mouse made it impossible to catch.