Superlative form of dry; the most dry or containing the least moisture of all things being compared.
From 'dry' (Old English 'dryge') with the superlative suffix '-est,' the oldest way of forming superlatives in English (still used for short adjectives like 'big,' 'small,' and 'dry').
English uses '-est' for short adjectives and '-most' for longer ones—you'd say 'dryest' but 'most beautiful'—and this rule hasn't changed in 1,000 years, making it one of our language's most stable features.
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