IPA: /əˈkrəʊməˌtɪkli/
KK: /əˈkrōˌma-tik-lee/
In a way that does not involve color or hue; relating to or characterized by the absence of color.
The colors were displayed achromatically, emphasizing the shapes and forms instead.
Achromatically → It is formed from "a-" (meaning without) and "chroma" (from Greek "chroma", meaning color) and "-tic" (meaning pertaining to). The word describes something that is without color or pertaining to the absence of color.
Think of 'without' ('a-') and 'color' ('chroma') to remember that 'achromatically' means relating to the absence of color.