Also found in: Thesaurus, Medical, Encyclopedia.


 (ăk′rə-măt′ĭk, ā′krə-)
1. Designating color perceived to have zero saturation and therefore no hue, such as neutral grays, white, or black.
2. Refracting light without spectral color separation.
3. Biology Difficult to stain with standard dyes. Used in reference to cells or tissues.
4. Music Having only the diatonic tones of the scale.

[From Greek akhrōmatos : a-, without; see a-1 + khrōma, khrōmat-, color.]

ach′ro·mat′i·cal·ly adv.
a·chro′ma·tic′i·ty (-tĭs′ĭ-tē) n.
a·chro′ma·tism (ā-krō′mə-tĭz′əm) n.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
References in periodicals archive ?
However, future studies need to be designed to determine the etiology related to why people see color information achromatically in the procedure for measuring stereopsis.
The LDM-9810 modularly designed viewer module is combined with the PD-16VI011 plug-in photometric detector and any proprietary optometer, forming an luminance measurement system that features a viewable and sizeable target spot A wide achromatically corrected 50-mm lens aperture objective and focusing feature satisfies the tightest requirements for the suppression of stray light and image formation.
Grayscale versions of these fused images (whg and bhg, respectively) were spatially identical to their chromatic counterparts but were rendered achromatically. Single-band JR images were of white-hot polarity.