To regret greatly or to feel deep sorrow about something; an archaic or dialect form of expressing regret.
From be- (prefix) + grett, which appears to be an archaic or dialectal form possibly related to 'grate' or expressing rough, harsh emotion. This is a rare word with limited historical documentation.
This is one of the rarest 'be-' words in English, barely appearing in historical texts. It shows how the 'be-' prefix could theoretically attach to almost any word to intensify meaning, but most such combinations never stuck around in common usage.
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