No moving/mechanical parts. The term electronic implies that analog and/or digital circuits are used to provide a solution. Electricity (electrons) activate semiconductor elements that change their state, but all the movement is at atomic levels. Electronic systems also imply some form of decision making or "intelligence" as in all computer-based devices.
Electromechanical and Electrical
Computers, smartphones and tablets are examples of electronic devices, whereas a keyboard and mouse are electromechanical devices because they have moving parts (keys, buttons, scroll wheels). Electricity used as raw power for heat, light and motors is considered electrical, not electronic.
From "Electron Tube"
Although coined earlier, "Electronics" magazine (1930) popularized the term electronic. The magazine subheading read "Electron Tubes - Their Radio, Audio, Visio and Industrial Applications." The term was derived from the electron (vacuum) tube. See semiconductor
, vacuum tube
, hardware circuit