apochromatPronunciation: /ˈapəkrəmat/Definition of apochromat noun Physics a lens or lens system that reduces spherical and chromatic aberration. Derivatives apochromaticPronunciation: /-krəˈmatɪk/ adjective Origin: early 20th century: from apo- + chromaticapochromat in other Oxford dictionaries Definition of apochromat in the US English dictionary