open letter

noun
  1. a letter, often of protest or criticism, addressed to a specific person, but intended to be brought to public attention.

Origin of open letter

First recorded in 1875–80
Related formso·pen-let·ter, adjective
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British Dictionary definitions for open letter

open letter

noun
  1. a letter, esp one of protest, addressed to a person but also made public, as through the press
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012