A superlative form meaning 'most good' or 'best,' though this is a non-standard construction in modern English.
From 'better' plus the superlative suffix '-most' (as in 'topmost' or 'foremost'). This is an archaic way of forming superlatives, now replaced by the standard 'best.'
Bettermost reveals how English grammar evolved—in Middle English, people could stack suffixes more freely to create superlatives, but over time, the language standardized to using just 'best' instead, showing how languages constantly simplify their options.
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