Aerial (Antenna) A device to receive or transmit radio signals. It is also known as an antenna.
Preset variable resistor A preset is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment. Presets are cheaper than standard variable resistors so they are sometimes used in projects to reduce the cost.
Light Emitting Diode A transducer which converts electrical energy to light. Usually abbreviated to LED.
Loudspeaker A transducer which converts electrical energy to sound.