Stealthy (adjective)

1. Acting or done in a covert or secretive way.
2. Moving or proceeding in a silent or unobtrusive way.

Origin:

From the old english word "stealth" meaning "the act of stealing, or taking something secretly".

Examples:

1. He entered the house in a stealthy manner, trying not to make any noise.
2. The burglar was stealthy, he didn't make any noise when he entered the house.
3. The spy was stealthy and able to gather information without being detected.
4. The animal is stealthy and can move quietly through the forest.
5. The company's new product launch was very stealthy, it was not announced until the last minute.