the.com/fountain pen

means A pen with a built-in reservoir of liquid ink that feeds continuously through a nib, instead of needing constant dipping.

from From 'fountain' in its old sense of a self-feeding source — like a water fountain that keeps flowing without a bucket refill. Pen-makers in the 1800s borrowed the word for their big innovation: a pen with its own internal ink supply, no inkwell required. Early versions leaked notoriously and were prone to blots, but the name stuck because the idea — ink that flows on its own, like water from a spring — was the whole selling point.