achromatic

ach·ro·mat·ic

adj \ˌak-rə-ˈmat-ik\

Definition of ACHROMATIC

1

: refracting light without dispersing it into its constituent colors : giving images practically free from extraneous colors <an achromatic telescope>

2

: not readily colored by the usual staining agents

3

: possessing or involving no hue : being or involving only black, gray, or white <achromatic visual sensations> <achromatic light stimuli>

—ach·ro·mat·i·cal·ly \-i-k(ə-)lē\ adverb