shadow:

1. a figure cast by intercepting light
2. comparative shade
3. mild suggestion
4. a ghost or phantom
5. an indistinct idea
6. an intimation
7. a reflected image
8. a period of doubt or pervasive threat
9. to shelter or protect
10. an inseparable companion
11. a detective, spy, or stalker
12. to secretly keep watch
13. without official authority
14. to cloud meaning
15. the absence of light
16. the darkest areas of a picture or photograph