solid state - technical definition

An electronic component or circuit made of solid materials, such as transistors, chips and bubble memory. There is no mechanical action in a solid state device, although an unbelievable amount of electromagnetic action takes place within.

Faster and More Reliable
For data storage, solid state devices are much faster and more reliable than mechanical drives that spin disk platters and tape reels, but they are more expensive. Although solid state costs continually drop, magnetic disks and optical discs also continue to improve their cost/performance ratio.

The first solid state device was the "cat's whisker" of the 1930s. A whisker-like wire was moved around on a solid crystal in order to detect a radio signal.