No, not a misspelling. The Theremin was invented by a Russian named Leon Theramin in 1920. It consists of two antennas that sense the position of the player's hands, which control amplitude and frequency. If you have ever watched classic 1950s SciFi B-movies, you have heard the weirdly eerie sounds of a Theremin many, many times.
IT is considered a very difficult instrument to play well, but anyone can have fun making Outer Limits sounds with a Theremin in a few minutes' time.
This one includes the power cord and an amp cord. You'll need your own amplifier or speaker system to plug it into to hear the sound.
You, too, can amaze your friends and give small children nightmares with this one for $125 shipped.