Young Brunette Girl With A Navel Piercing Reveals In The Shadow Of A Palm Tree

Shadow as a term is often used for any occlusion, not just those with respect to light. For example, a rain shadow is a dry area, which, with respect to the prevailing wind direction, is beyond a mountain range; the range is "blocking" water from crossing the area. An acoustic shadow can be created by terrain as well that will leave spots that can't easily hear sounds from a distance. Sciophobia, or sciaphobia, is the fear of shadows.
Mythological connotations
An unattended shadow or shade was thought by some cultures to be similar to that of a ghost.