1. An electric generator, especially for direct current.
2. An energetic, hardworking, forceful person.
Deriving from the Greek dunamis, meaning “power,” dynamo is a nifty little word. It can stand in for “generator,” perhaps in a laboratory or ship scene. Much like the word “firecracker,” it can also be used to describe a person – usually someone who’s quite powerful or dynamic.
Reluctantly he withdrew his eyes from the mysterious sphere and looked about the room once more. No, the laboratory was vacant human occupants. No one was hidden among the benches that were cluttered with beakers and test tubes and stills, or among the dynamos and transformers in the other end of the room.
– Jack Williamson, “The Pygmy Planet” (1932)