indigoid

Indigoid is a term used to describe colors that resemble indigo or are indigo-like, lying between blue and violet on the visible spectrum. The word is formed from indigo and the suffix -oid, meaning "like."

In color theory, indigoid hues are typically deep and saturated, with a bluish-purple character. They are perceived as darker and more purplish than ordinary blue, and they sit near the boundary between blue and violet rather than in the pure blue region.

Applications include design, fashion, and printing, where indigoid tones are used to convey depth, mystery, or formality. In dye chemistry, the term can denote indigoid dyes and pigments—colors derived from or related to indigo.

Indigoid is informal and not part of a standardized color system; specific shades are described using other naming schemes in web colors, paints, and textiles.

Related terms include indigo and indigo dye, which refer to the exact color or the traditional dye, while indigoid describes a broader, indigo-like range in color practice and chemistry.