Apochromat

An apochromat, or apochromatic lens (apo), is a photographic or other lens that has better correction of chromatic and spherical aberration than the much more common achromat lenses. ==Explanation== Chromatic aberration is the phenomenon of different colors focusing at different distances from a lens. In photography, chromatic aberration produces ...
Found on http://en.wikipedia.org/wiki/Apochromat

Apochromat

A lens consisting of three or more elements which gives a greater reduction of chromatic abberation than that of a two-element (Achromatic) lens.
Found on http://www.encyclo.co.uk/local/20448

Apochromat

Lens corrected for chromatic aberration in all three primary colors.
Found on http://www.superglossary.com/Glossary/Entertainment/Photography/
No exact match found