A non-standard or archaic superlative form meaning 'most evil,' though 'most evil' is the standard modern form.
From 'evil' plus the superlative suffix '-est', following the ancient English pattern used in words like best, worst, and greatest. Modern English tends to use 'most evil' instead.
The shift from '-est' endings to 'most' words shows language evolution in real-time—as adjectives got longer, English speakers naturally adapted their grammar, and eventually dictionaries caught up to reflect common usage.
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