Common:
* Ballpen: A pen with a ballpoint tip.
* Fountain pen: A pen with a nib that uses ink from a cartridge or reservoir.
* Penknife: A small pocketknife with a blade that folds into the handle.
Less Common:
* Inkpen: A general term for a pen that uses ink.
* Sketchpen: A type of pen used for drawing and sketching.
* Felt-tip pen: A pen with a felt tip that releases ink.
* Cigarette lighter pen: A pen that also functions as a cigarette lighter.
* Push-button pen: A pen with a button to push for ink flow.
* Rollerball pen: A pen with a ballpoint that uses liquid ink.
Figurative/Idioms:
* Pen-pusher: A derogatory term for someone who does boring or routine office work.
* Pen-friend: Someone you correspond with regularly by letter.
Let me know if you'd like more!