light·fast
ˈlīt-ˌfast 
: resistant to light and especially to sunlight
especially
: colorfast to light
light·fast·ness
plural -es
: ability to resist change by light and especially by sunlight
specifically
: resistance to fading or change of color by light
violet shades of outstanding lightfastness
testing dyed materials for lightfastness
Examples of lightfast in a Sentence
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Literary Hub, 2 Apr. 2026
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Adjective
Synthetic dyes were more colorfast, lightfast, and consistent than natural dyes, and the industry boomed.
—Literary Hub, 2 Apr. 2026
Cite this Entry
“Lightfast.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lightfast. Accessed 18 Jun. 2026.
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