This refers to the definition of Critical Infrastructures and Critical Infrastructure Sectors by nations. Alternatively, the term National Critical Infrastructure is used.
Critical National Information Infrastructure (CNII) are those assets (real and virtual), systems and functions that are vital to the nations that their incapacity or destruction would have a devastating impact on: (1) National economic strength, (2) National image, (3) National defense and security, (4) Government capability to functions, and (5) Public health and safety. 
Critical National Infrastructure can be defined as being of unique national importance, which if disrupted or destroyed would have significant national level effects and may impact across a number of sectors. 
CNI is evaluated as a level 5 on the Criticality Scale (Table 6). CNI is a subset of C I.
Critical National Infrastructure is an asset, system or part thereof located in Member States which is essential for the maintenance of vital societal functions, health, safety, security, economic or social well-being of people, and the disruption or destruction of which would have a significant impact in a Member State as a result of failure to maintain those functions. 
Critical National Information Infrastructure (CNII) is defined as those assets (real and virtual), systems and functions that are vital to the nations that their incapacity or destruction would have a devastating impact on: (1) National economic strength; Confidence that the nation's key growth area can successfully compete in global market while maintaining favourable standards of living; (2) National image; Projection of national image towards enhancing stature and sphere of influence. (3) National defence and security; guarantee sovereignty and independence whilst maintaining internal security. (4) Government capability to functions; maintain order to perform and deliver minimum essential public services. (5) Public health and safety; delivering and managing optimal health care to the citizen. 
Critical infrastructure/critical national infrastructure: Physical and digital assets, services, and supply chains, the disruption (loss, compromise) of which would severely impact the maintenance of national security, public safety, fundamental rights, and well-being of all New Zealanders. 
Critical national infrastructure is a term used by governments to describe assets that are essential for the functioning of a society and economy (e.g. electricity generation, gas production, telecommunications, water supply etc.). 
Critical national infrastructure refers to infrastructure or part of the economy whose failure or breakdown would have enormous consequences on national security or the economic and/or social welfare of a nation. 
Critical National Infrastructure: Those critical elements of infrastructure (namely assets, facilities, systems, networks or processes and the essential workers that operate and facilitate them), the loss or compromise of which could result in:
a) Major detrimental impact on the availability, integrity or delivery of essential services – including those services whose integrity, if compromised, could result in significant loss of life or casualties – taking into account significant economic or social impacts; and/or
b) Significant impact on national security, national defence, or the functioning of the state. 
[old definition] Critical National Infrastructure is a sub-set of critical infrastructure, and describes those elements of critical infrastructure which have been identified by Government as being of strategic national importance to essential service delivery; the loss or compromise of these assets would have a severe, widespread effect, impacting on a national scale.  
Critical National Infrastructure is those facilities, systems, sites and networks necessary for the functioning of the country and the delivery of the essential services upon which daily life in the UK depends. 
Critical Infrastructure (CI): Assets that the Government has identified within the nine National Infrastructure sectors (energy, food, water, government, transportation, communication, emergency services, health care and finance) as being of strategic importance to essential service delivery. The loss or compromise of these assets would lead to severe economic and / or social consequences and / or to loss of life across significant parts of the UK. 
CNI is defined as those infrastructure assets (physical or electronic) that are vital to the continued delivery and integrity of the essential services upon which the UK relies, the loss or compromise of which would lead to severe economic or social consequences or to loss of life. 
Critical National Infrastructure: processes, systems, facilities, technologies, networks, assets and services essential to the nation’s health, safety, security or economic well-being and the effective functioning of government. 
Critical infrastructure can be stand-alone or interconnected and interdependent within and across national borders. Disruptions of critical infrastructure could result in catastrophic loss of life, adverse economic effects and significant harm to public confidence.