Mechanical instrument - meafaigaluega; musical instrument - meafaifaili or meafaili.

it is a device that converts mechanical into electric measurements. it measures velocity. there are many types: electrical, mechanical, thermo-electrical... for example the mechanical tachometer converts the rotation motion into translation motion with the help of an axis so you can read it on the scale of the tachometer. sorry for not being so good at explaining this. hope somebody will be more documented.

a mechanical designer designs and make mechanical things

A robot consist mechanical and non-mechanical both

Mechanical devices mostly symbolize the parts, joints, rigid structures in it... they mostly symbilize the tough mechanical components therefore call as mechanical :)