I believe your question is: what is the correct acronym for a piece of technology wherein most of the devices electronics are located, if not all?
The correct answer is none other than the MOTHERBOARD. The motherboard, coming from the root word mother, has almost all of the device's electronics. Take your personal computer for example; if you open your CPU or central processing unit, you will find the motherboard at the centermost part of the CPU. On it, you will see modularized components such as the fan, the RAM slots, the video card slot/s, etc.
The motherboard is also the most important part of your device! In most cases, if a liquid substance is introduced on the motherboard, the liquid substance will corrode the fine electronics soldered on it thus busting it. Static also damages the motherboard if careless contact between the user and the board occurs.