Stealthily is defined as something done secretly, slyly or in a manner designed not to attract notice. Creeping around silently in the dark to avoid being noticed as you enter a building is an example of a time when you enter stealthily.

When you eat dirt for the first time and leave your family to build a shack in the woods

When something is there, but not really there. Able to be present but not seen or disguised as something else.