Balun

From Gentoo Linux Wiki

From The Free On-line Dictionary of Computing (27 SEP 03) :

balun 

A transformer connected between a balanced source or load and an unbalanced source or load. A balanced line has two conductors, with equal currents in opposite directions. The unbalanced line has just one conductor; the current in it returns via a common ground or earth path. (1996-10-17)