One of the mysteries of the English language finally explained.
1A blue gown worn as part of a person's uniform; specifically (a) one worn by a convicted prostitute in a house of correction; (b) one worn by a person who is provided for at a charitable institution, or (Scottish) by a licensed beggar. Compare "blue coat". Now chiefly historical.
2A person who wears a blue gown, especially as part of a uniform; (Scottish) a licensed beggar (the blue gown being a symbol of his or her license to beg). Compare "blue coat". Now historical.
Late 16th century; earliest use found in George Whetstone (d. 1587), writer. From blue + gown.
blue gown/ˈbluː ɡaʊn/
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