Mecha was the general term for any vehicle that has large-scale robotic or bioengineered limbs.
Types of mecha
Robotech Defense Force
Robotech Expeditionary Force
Robotech Federation
Imperial Zentraedi Forces
Robotech Masters
Invid
Behind the Scenes
The Japanese usage of "mecha" differs from it's western usage. There, a "mecha" can mean anything from Petite Cola robotic vending machines to the Macross.