shadow

A shadow is the dark area that is made when something blocks light, and that is shaped like the thing blocking the light.

Example: I saw your shadow against the wall.

The darkness in a shadow.

Example: The room filled with shadow as the night came.

If you shadow someone, you follow them closely without their knowing it.

Example: The detective shadowed the thief.

If something is being shadowed, it is being covered in shadow or made dark.

Example: The curtains shadowed the room.

If you shadow someone, you accompany them when they are working so as to learn about an occupation you intend to take up.