To strip skin from flesh, or to criticize harshly and mercilessly.
From Old English flean, related to Old Norse fla (to skin). The metaphorical sense of harsh criticism developed from the literal act of stripping away protective covering.
The word 'flay' connects physical and emotional violence in a uniquely visceral way - when we say someone was 'flayed alive' by criticism, we're using an ancient metaphor that equates harsh words with the literal removal of protective skin.
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