Ap`la*nat"ic (#), a. [Gr. priv. + disposed to wander, wandering, to wander.] Opt.
Having two or more parts of different curvatures, so combined as to remove spherical aberration; -- said of a lens.
Aplanatic focus of a lens Opt., the point or focus from which rays diverging pass the lens without spherical aberration. In certain forms of lenses there are two such foci; and it is by taking advantage of this fact that the best aplanatic object glasses of microscopes are constructed.
© Webster 1913.