shadow
noun
shade within clear boundaries
an unilluminated area
“he moved off into the darkness”
something existing in perception only
“a ghostly apparition at midnight”
a premonition of something adverse
“a shadow over his happiness”
an indication that something has been present
“there wasn't a trace of evidence for the claim”
“a tincture of condescension”
refuge from danger or observation
“he felt secure in his father's shadow”
a dominating and pervasive presence
“he received little recognition working in the shadow of his father”
a spy employed to follow someone and report their movements
an inseparable companion
“the poor child was his mother's shadow”
verb
follow, usually without the person's knowledge
“The police are shadowing her”
cast a shadow over
make appear small by comparison
“This year's debt dwarfs that of last year”
Source: WordNet 3.1, Princeton University