the invariable or characteristic accompaniment or companion of a person or thing.
the complete or perfect shadow of an opaque body, as a planet, where the direct light from the source of illumination is completely cut off. Cf.penumbra(def. 1a).
the dark central portion of a sunspot. Cf.penumbra(def. 1b).
a phantom or shadowy apparition, as of someone or something not physically present; ghost; spectral image.