The quality or state of being discolored; the condition of having lost or spoiled color.
From discolored + -ness (the suffix that forms nouns expressing a state or quality). This creates a noun describing the abstract quality of discoloration.
The suffix -ness is one of English's favorite tools for turning adjectives into nouns about qualities—'discoloredness' is the state of being discolored, just like 'sadness' is the state of being sad!
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