Definition
Means: Means the ability of network and information systems to resist, at a given level of confidence, any action that compromises the availability, authenticity, integrity or confidentiality of stored or transmitted or processed data or the related services offered by, or accessible via, those network and information systems
Source
Point (2) of Article 4 of Directive (EU) 2016/1148 of the European Parliament and of the Council of 6 July 2016
Link
https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016L1148&rid=1