Superlative form: most fretty; extremely worried, nervous, or displaying the most pronounced fret patterns.
From 'fretty' (adjective) + the superlative suffix '-est', forming the strongest degree of comparison in English adjectives.
The superlative '-est' is one of English's oldest grammatical features, shared with German and Dutch—it goes back to Proto-Germanic, making words like 'frettiest' descendants of ancient word-formation rules.
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