noun

• The effect of being shadowed (in the sense of blocked), as from a light source or radio transmission.
• The situation where an individual repeats speech immediately as they hear it (usually through earphones).
• (espionage) Secretly or discreetly tracking or following someone, keeping under surveillance.
• A faint representation; an adumbration.
• (computing) The technique of copying ROM contents to RAM to allow for shorter access times. The ROM chip is then disabled while the initialized memory locations are switched in on the same block of addresses.
• (education) A work experience option where students learn about a job by walking through the work day as a shadow to a competent worker.