The state or quality of being besotted; drunkenness, infatuation, or foolishness.
From 'besotted' plus the suffix '-ness,' which creates abstract nouns from adjectives to denote a state or quality.
English's '-ness' suffix is so powerful that you could theoretically add it to almost any adjective to create a noun—'besottedness' shows how productive this pattern is even with rare words!
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