CCI has developed working definitions* related to critical infrastructure as follows:
Critical Infrastructure includes includes systems, facilities, and assets so vital that if destroyed or incapacitated would disrupt the security, economy, health, safety, or welfare of the public. Critical infrastructure may cross political boundaries and may be built (such as structures, energy, water, transportation, and communication systems), natural (such as surface or ground water resources), or virtual (such as cyber, electronic data, and information systems).
All-Hazards include events and conditions such as infrastructure deterioration, natural disasters, accidents and malevolent acts that have the potential to cause injury, illness, death, damage or disruption of services.
Mutihazards denote the relevant environmental or manmade conditions that are used for engineering analysis and design. A sound multihazard approach to engineering practice will provide infrastructure resilience to all-hazards risk.
Resilience refers to the capability to mitigate against significant all-hazards risks and incidents and to expeditiously recover and reconstitute critical services with minimum damage to public safety and health, the economy, and national security.
*See ASCE Policy Statement 518, Unified Definitions for Critical Infrastructure and Sensible Security