stop up
verb
High School
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.
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.