noun
: a hole in a retaining wall, canal paving, or other structure to drain off accumulated water which might otherwise induce inordinate pressure back of or under the structure
noun
: a hole in a retaining wall, canal paving, or other structure to drain off accumulated water which might otherwise induce inordinate pressure back of or under the structure
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012