A pilonidal cyst is a unique kind of abscess that occurs in or above the crease of the buttocks. Pilonidal cysts often begin as tiny areas of infection in the base of the area of skin from which hair grows (the hair follicle).
Cofferdam A cofferdam is a temporary enclosure built within, or in pairs across, a body of water and constructed to allow the enclosed area to be pumped out, creating a dry work environment for the major work to proceed.
aqueduct--a pipe, conduit, or channel designed to transport water from a remote source, usually by gravity. aquifer--a geologic formation(s) that is water bearing. A geological formation or structure that stores and/or transmits water, such as to wells and springs. Use of the term is usually restricted to those water-bearing formations capable of yielding water in sufficient quantity to constitute a usable supply for people's uses. aquifer (confined)--soil or rock below the land surface that is saturated with water.