A small opening left in the vertical joints of masonry walls to allow water that has penetrated the wall to drain out. Weep holes are typically placed at the base of walls, above flashing, and at other locations where water may accumulate. Proper placement and maintenance of weep holes are essential for effective moisture management in masonry walls.
http://www.wikidata.org/entity/Q6142287, https://en.wikipedia.org/wiki/Weep_(architecture), https://www.google.com/search?kgmid=/m/02vy_11&hl=en, https://www.google.com/search?kgmid=/m/05yhdq&hl=en