denial

/di-ˈnī(-ə)l/

noun

  1. refusal to satisfy a request or desire

  2. refusal to admit the truth or reality of something (such as a statement or charge)

  3. assertion that an allegation is false

the denial of privileges

noun

  1. rejection of the idea that changes in the Earth's climate or weather patterns are caused by human activity

noun phrase

  1. an attempt to interfere with the normal operations of an online service (such as a website or app) by overwhelming it with repeated automated requests for data from multiple sources —abbreviation DDoS

Although computer viruses, worms and other so-called malware can be countered with good security practices and up-to-date defensive software, distributed denial of service attacks are hard to protect against.