This is a bit of a trick question! The word "mechanical" is used to describe devices that use physical forces and motions to operate. So, the reason why mechanical devices are "mechanical" is simply because that's what they are!

Here's a way to think about it:

* "Mechanical" means relating to or caused by physical forces and motions.

* Mechanical devices work by using these physical forces and motions (like gears, levers, springs, etc.)

Let me know if you have a more specific question about mechanical devices, like why they were developed or what made them different from other types of technology!