APLACOPHORA
Ap`la*coph"o*ra, n. pl. Etym: [NL., fr. Gr. (Zoöl.)
Defn: A division of Amphineura in which the body is naked or covered with slender spines or setæ, but is without shelly plates.
APLANATIC
Ap`la*nat"ic, a. Etym: [Gr. (Opt.)
Defn: 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.
APLANATISM
A*plan"a*tism, n.
Defn: Freedom from spherical aberration.
APLANOGAMETE
A*plan`o*ga*mete", n. (Bot.)
Defn: A nonmotile gamete, found in certain lower algæ.
APLASIA
A*pla"si*a, n. [NL.; Gr. priv. + a molding.] (Med.)
Defn: Incomplete or faulty development.