Shad
the popular name of three anadromous fishes of the genus Clupea: (1) The allice or European shad. (2) The American shad, C. sapidissima, an important food fish, abundant on the At- SHAD and California. Grapefruit or pomelo is a variety of shaddock.
SHADOW. (1) Shade within defined limits; the figure of a body projected on the ground, etc., by the interception of light; obscurity or deprivation of light, apparent on a surface or plane, and representing the form of the body which intercepts the rays of light. (2) Darkness, gloom, shade, obscurity. (3) The dark part of a picture; the representation of comparative deficiency or deprivation of light; shade. (4) A reflected image, as in a mirror or water, hence, any image or portrait.
In optics, shadows are, theoretically considered, of two kinds, geometrical and physical. If a shadow be supposed to be produced by the interception of light proceeding from a single mathematical point, it will be well defined by straight lines proceeding from the point, and grazing the intervening object. But as every luminous body is possessed of some magnitude, and, therefore, emits light from many points, the shadow is not precisely defined, but consists of a portion in perfect shadow, or to which no luminous rays have access, and penumbra, to which some rays have access. In the former case the theoretical shadow is a geometric one, in the latter physical, i. e., such as actually occurs in nature.