Each of the colours into which white light is split by a prism (conventionally regarded as seven in number); colour such as that produced by a prism from white light; frequently in plural.
Origin
Early 18th century.
Definition of prismatic colour in US English:
prismatic colour
(USprismatic color)
noun
Each of the colours into which white light is split by a prism (conventionally regarded as seven in number); colour such as that produced by a prism from white light; frequently in plural.