In secret, privately. For example, The nominating committee always meets behind closed doors, lest its deliberations become known prematurely. Also see behind the scenes.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use behind closed doors in a sentence
But on the Nation, these are the kinds of stories only whispered behind closed doors.A Shooting on a Tribal Land Uncovers Feds Running Wild | Caitlin Dickson | August 26, 2014 | THE DAILY BEAST
But behind closed doors, corporate influence peddlers are more powerful than ever.
The transcripts show that that question was answered—back in March—behind closed doors by the two military officials responsible.
One thing I wish we could have included was the more rough physical abuse that many of the students suffered behind closed doors.‘Kidnapped for Christ’ Review: Come Because You’re Gay, Stay For Jesus | Matthew Paul Turner | July 11, 2014 | THE DAILY BEAST
This tension between committees has often played out inside the Republican conference, behind closed doors.
The meetings were held secretly behind closed doors because of the grave problems which the convention had to solve.Hallowed Heritage: The Life of Virginia | Dorothy M. Torpey
Let the child early learn that good wholesome play in the open is better than secretive misdemeanor behind closed doors.The Mother and Her Child | William S. Sadler
The sessions of both bodies were to be held behind closed doors.A History of the Nineteenth Century, Year by Year | Edwin Emerson
And I went again and again, until the House sat behind closed doors.Richard Carvel, Complete | Winston Churchill
At 2:30 o'clock a secret meeting of the officers of the several labor lodges and Captain O'Connor was held behind closed doors.The Harris-Ingram Experiment | Charles E. Bolton