Indigo or Indigo is the traditional denomination of the very dark and deep varieties of the blue color ; formerly it was also said glasto. Indigo or Indigo are also the colors that are perceived when photoreception of a light whose dominant wavelength measures between 420 and 450 nm.2 Originally, indigo or indigo was a predominantly textile dye whose color, by extension, was called also like this. This coloration began to be considered part of the spectrum of visible light and therefore of the rainbow, when Isaac Newton gave the color denomination “indigo” to the dark blue band of the spectrum.
Etymology
“Indigo” derives from the Latin indĭcus, ‘from India’, because this dye was imported from there. You have probably entered the Castilian language via Genoese or Venetian. It appears in our language in 1555, in the Indic form.
The word “indigo” comes from the Hispanic Arabic anníl or annír , this from the classical Arabic níl [aǧ], this from the Persian nil, and this from the Sanskrit nīla. Its use in the Spanish language dates back to the 13th century.
