Back planes refer to the circuit boards that are installed at the back of electronic devices. These boards serve as a backbone for signal distribution and are essential for the functionality of the electronic equipment. There are different terms that can be used instead of 'back planes.' Some of the synonyms for back planes are motherboard, backboard, backplane assembly, backpanel, and circuit plane. Depending on the context and the type of electronic equipment, these terms may be used interchangeably. It is essential always to try to use the appropriate terminology to avoid ambiguity and misunderstanding in the field of electronics.