transmitting light without dispersing it into its constituent colours
an achromatic lens
possessing no hue; neutral
Grey is an achromatic colour
in music, having no sharps or flats
achromatically adv
achromaticity /əˌkrohməʹtisiti/ noun
achromatism /əʹkrohmətiz(ə)m/ noun
[French achromatique from Greek achromatos, from a-2 + chromat-, chroma colour]