ABYSSAL a.
one of the belts or zones into which Sir E. Forbes divides the bottom of the sea in describing its plants, animals, etc. It is the one furthest from the shore, embracing all beyond one hundred fathoms deep. Hence, abyssal animals, plants, etc.
ACHROMATIC a.
Uncolored; not absorbing color from a fluid; -- said of tissue. Achromatic lens (Opt.), a lens composed usually of two separate lenses, a convex and concave, of substances having different refractive and dispersive powers, as crown and flint glass, with the curvatures so adjusted that the chromatic aberration produced…