Definition of "stop up" [stop up]

• To fill a hole or cavity, or block an opening or passage, as with a plug. (verb)
• 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. (verb)

Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License

• "The business of the modelling clay from the art-room which had been used to stop up the waste-pipe reacted for and against Smith, Mrs. Bradley decided."
• "Still another adventure befell us at sea; for my Lord Dragonès, a rich man of Provence, was sleeping one morning in his ship, which was about a league ahead of ours; and he called one of his squires, and said to him: "Go and stop up that opening, for the sun is in my eyes.""
• "“So that anybody who knew there was a lump of modelling clay in the art-room could have slipped in and taken enough to stop up that waste-pipe,” she said."