An enclosure within which electric circuits are connected.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "junction box" in a sentence
"Tracking the wire to the boiler room in the basement, he found a new electrical connection off the junction box and a radio hidden behind a bin of soft New Mexican coal."