From Longman Dictionary of Contemporary Englishfountain penˈfountain pen noun [countable] 
DTCa pen that you fill with ink → ballpoint
DTCa pen that you fill with ink → ballpointExamples from the Corpus
fountain pen• Silver cufflinks are £49.92, and a Waterman 100 fountain pen is £120.• Silk tie, £55, silver and gold sun cufflinks, £295, blue and gold fountain pen, £105, Gucci.• There was a silence, the Matron, who was a Miss Cress, tapping her fountain pen lightly on the blotter.• On Wednesday after the selection committee meeting, I realized I'd left my fountain pen in here.• All he can say for certain, therefore, is that Black is writing in a notebook with a red fountain pen.• The writer of the best letter each month will be presented with a Montblanc Solitaire fountain pen. 