What does dichromatic mean?
Dichromatic is an adjective describing anything that involves, consists of, or is perceived in two colours. Its most precise scientific use is in vision research: an animal with dichromatic vision possesses only two functioning types of retinal cone cells rather than the three that normal human trichromatic vision relies on. Most mammals, including familiar pets such as dogs and cats, are dichromats, perceiving the world largely in blues and yellows; certain kinds of human colour blindness are likewise dichromatic. Beyond biology, the word appears in optics, where a dichromatic system or filter works with two distinct wavelengths of light, and in design or photography, where it may simply describe a strikingly two-toned image. Derived from the Greek roots di- ('two') and chroma ('colour'), it carries a technical, precise tone and pairs naturally with terms like vision, display, and filter.
Involving, consisting of, or perceived in two colours.
"The museum's dichromatic logo paired deep navy with bright orange."
(Of vision) depending on two cone types rather than three, so that colours are distinguished along one dimension only.
"Dichromatic primates cannot distinguish red from green."
This is the dominant sense in scientific literature on colour vision.
Most dogs are dichromatic — they see the world the way a red–green colour-blind person does, in a two-colour palette of blues and yellows.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dichromatic
Dichromatic comes from the Greek elements di-, meaning 'two', and chrōma (genitive chrōmatos), meaning 'colour' or 'pigment'. It was formed on the pattern of chromatic, entering English in the nineteenth century alongside related terms such as monochromatic and trichromatic as scientists developed vocabulary for describing colour vision and optics. It shares its Greek root with words such as chromosome, literally 'colour body', named for how readily they stain with dyes.
Related word forms
How dichromatic is actually used
Chiefly technical or scientific register, common in vision science, zoology, optics, and photography; in general use it often appears simply to mean 'two-coloured'. In vision science it specifically denotes colour perception mediated by two cone types, as in deuteranopia and protanopia.
Easily confused with dichromatic
Trichromatic refers to normal human colour vision based on three cone types (or three-colour processes), whereas dichromatic involves only two.
Monochromatic describes a single colour or shades of one hue, while dichromatic involves exactly two.