Denial of Service

(abbreviated DoS) refers to an attack on a computer system in which the attacker attempts to overload the victim directly (DoS) or distributed via several attackers (Distributed Denial of Service, abbreviated DDoS) or via external Internet services with a large number of requests (e.g. e-mails) in such a way that the target system can no longer respond in a regular manner.

Source: logipedia / Fraunhofer IML