The importance of safety-related technology applications has increased in the last years - not least because of laws and regulations intended to ensure the safety and integrity of goods and persons. More and more people are asked to gain and improve their knowledge of safety-related technologies. Safety-related technology, however, has its own terminology which clearly differs from ordinary language terms. Did you know, for instance, that redundant systems can also be completely unsafe from a safety-related view point? Faults in safety-related systems can endanger human life and cause financial and environmental damage. Safetyrelated technology is intended to counteract this danger. Safety-related systems are increasingly used in almost all technical areas and are implemented in complex control and automation systems of all industrial branches. In terms of safety, a safe system is a system with a specific fault reaction, e.g., it is fail-operational in case of aircrafts, failsafe in case of trains or fault-tolerant such as autopilots. Depending on the requirements, safety-critical architectures are usually very complex. This applies both to the hardware and the software, the overall development process and the tools in use. This comprehensive dictionary allows rapid access to essential information about the most used terms from numerous application areas. It provides accurate and precise explanations to over 2000 safety-related technology keywords and notes to their sources, generally standards and regulations. A variety of references allows the readers to recognise their correlations and developments.