Meaning of stop up | Babel Free

Definitions

1. To fill a hole or cavity, or block (an opening or passage), as with a plug.
2. To permanently close or block (a road or path); to legally extinguish a right of way.
   UK
3. To increase the aperture of a photographic lens, moving from an f/stop represented by a higher number to an f/stop represented by a lower number and causing more light to pass into the camera.

Examples

“So then we […] scratched around and found an old tin washpan, and stopped up the holes as well as we could.”

“To stop down means to narrow the aperture; to stop up or open up means to expand it.”

CEFR level