tapper

noun

1. a person or thing that taps or strikes lightly.
2. a telegraph key.

noun

1. a person or thing that taps, as trees for the sap or juice, a blast furnace, cask, or other container for their contents, etc.
2. a person who cuts screw threads into the surface of a circular opening, as of a pipe, nut, etc.

noun

1. a person who taps
2. a tool or instrument that taps
3. Northern English dialect an unstable and violent person