blue box

plural blue boxes

1. CanadaUKA blue container used for the collection of household waste (such as tin cans and newspapers) for recycling by a municipal authority.
2. historicalcommunicationsAn electronic device used to bypass payment on a tone pulse telephone system.

   1 more example

   This was before Wozniak—known among the cognoscenti as Woz—almost woke up the Pope by calling the Vatican on his famed illegal "blue box," before he invented the Apple II and helped launch the personal computer industry, and before he gave up his brilliant engineering career and became a public school teacher.

   1998 September, Gary Wolf, “The World According to Woz”, in Wired, archived from the original on 10 Aug 2011

3. USinformalclimatologyA "tornado watch" notification category.

   See also: severe thunderstorm watch

4. USabbreviationellipsispostalEllipsis of USPS blue box.
5. Used other than figuratively or idiomatically: see blue, box.