lightfast

[lahyt-fast, -fahst]

adjective

1. not affected or faded by light, lights, especially sunlight; colorfast when exposed to light. lights.

Other Word Forms

• lightfastness noun

Word History and Origins

Origin of lightfast¹

First recorded in 1955–60; light ¹ + fast ¹

Example Sentences

The cathedral received one of 12 copies of the “Apostle’s Edition” of the Bible, produced on 100% cotton paper using what its creators say is “lightfast ultraviolet ink” that dries “instantly on the press” before another color is applied.

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Ironically, the red paint made decades ago was relatively lightfast, because the color came from iron oxide, which keeps its color in the sun just as red, iron-rich soil found in some parts of the country does.

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Wax-based pigments tend to be lightfast, but watercolors and markers fade, so their tints will need to be corrected as well.

Read more on Scientific American