Element

An elementary device to create a circuit or a system is
called element. Elements are, for instance,
a wire
resistor
capacitor
inductor
diode
transistor
transforming elements:
microphone, loudspeaker,
Hall element, Peltier element, ...
Elements are considered to be discrete, but no means
lumped, i.e. a transmission line or a single antenna are
considered to be elements.