an electronic device used by phone phreaks to send out signals that unlock long-distance telephone circuits.
Origin of blue box
First recorded in 1975–80
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for blue box
Canadian a blue plastic container for domestic refuse that is to be collected and recycled
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