Definition of zero-day in English:

zero-day

adjective

Computing
  • Deriving from or relating to a previously unknown vulnerability to attack in some software.

    ‘the service is designed to detect all manner of malware, including zero-day threats’
    • ‘The point seemed to be to create a zero-day exploit, which he didn't have a chance of managing.’
    • ‘There were unexpected zero-day attacks causing a half-day network outage.’
    • ‘We're offering zero-day protection, stability, and configuration control.’
    • ‘The amalgamation of zero-day threats, compliance demands, and still more problems pushes corporations to address the most pressing challenges first.’
    • ‘Zero-day protection, spyware detection, protection for outbound data and excellent reporting tools are crucial to protect your networks.’
    • ‘Last week, the company warned the public of a "zero-day" attack that acts upon certain weaknesses in the program.’