The act or action of proceeding furtively, secretly, or imperceptibly. (Merriam – Webster)
The state of being furtive or unobtrusive. (Merriam – Webster)
Secret, clandestine, or surreptitious procedure. (Dictionary.com)
A furtive departure or entrance. (Dictionary.com)
Movement that is quiet and careful in order not to be seen or heard, or secret action. (Cambridge Dictionary)
Cautious and surreptitious action or movement. (Oxford Dictionaries)
For Tobacco, Stealth Marketing Is the Norm.