blue john


Definition of blue john

1 : a fibrous or columnar variety of fluorite found in Derbyshire, England and used especially for vases
2 sometimes capitalized J, dialectal : skim milk especially : milk that is just beginning to sour

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History and Etymology for blue john

from the name John

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Cite this Entry

“Blue john.” Dictionary, Merriam-Webster, Accessed 11 Jul. 2020.

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