Annular Space 4 : The space around a pipe (casing or tubing) suspended in a wellbore is often termed the ANNULUS, and its outer wall may be either the wall of the borehole or the casing. (ITOGP)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}