Main Entry: ach·ro·mat·ic

Pronunciation: \ˌak-rə-ˈmat-ik\

Function: adjective

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