Superlative form of fusty; most musty, moldy, and stale-smelling; most old-fashioned or hopelessly stuffy.
From fusty with the superlative suffix -est. This form represents the highest degree of the quality of staleness, mustiness, or outdatedness.
When you call someone 'the fustiest old codger,' you're using an insult that literally describes them as if they smell like a centuries-old cellar—English insults often work by comparing people to unpleasant smells and textures.
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