Pronunciation: [ˈakɹə͡ʊmə] (IPA) 
"Achroma" is a term derived from the Greek language, which means "without color." The correct spelling of this word is /eɪˈkroʊmə/ in IPA phonetic transcription. It is spelled with an "a" and not an "e" because the "c" in "achroma" is followed by an "h," resulting in a hard "k" sound. This is why the "a" is needed to produce the "ay" sound. Additionally, the "o" is also used instead of "a" to indicate a long vowel sound.
Achroma is a term used in various fields, including science, art, and medicine, to describe the absence or lack of color. Derived from the Greek words "a" meaning without or absence, and "chroma" meaning color, achroma signifies a condition or state where no hues, shades, or pigments are present.
In the realm of science, achroma refers to an object or substance that reflects or absorbs all wavelengths of visible light, resulting in a colorless appearance. This can be observed in achromatic materials such as white light or the gray scales of a black and white photograph. In art, achroma represents a monochromatic palette limited to shades of black, white, and gray. Artists may utilize achromatic color schemes to convey a sense of simplicity, neutrality, or elegance.
In medical contexts, achroma can also describe visual impairments. In particular, individuals affected by achromatopsia or total color blindness lack the ability to perceive or distinguish colors, resulting in a perception limited to black, white, and shades of gray. Achromatopsia is a rare congenital condition caused by the absence or dysfunction of cone cells in the retina.
Overall, achroma describes an absence of color and is employed in various disciplines to denote colorlessness, monochromatic palettes, and color vision deficiencies.
Leucoderma.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word achroma is derived from the Greek roots a- meaning without or not, and chroma meaning color. Therefore, achroma literally means without color or colorless.
