Official European Definition
Mutually reliant relationship between entities (objects, individuals, or groups) . The degree of interdependency does not need to be equal in both directions. For example, the Energy Sector depends on a functioning Water Sector for successful day-to-day operations, just as the Water Sector needs energy to effectively manage water and wastewater systems .
- DHS Risk Lexicon 2010 Edition, September 2010
- Critical Infrastructure Protection and Resilience Toolkit (Glossary), US Department of Homeland Security
- Unpublished working glossary of UP KRITIS and BSI, 2014