The article provides an analysis of the use of «Hazard» and «Risk» terms and associated phrases in legal and regulatory-technical documents and safety practices; their possible interpretations are identified. Most often, such problems arise during the classification of productions and facilities in accordance with their level of hazard, when various documents and articles use such terms as hazard degree, risk degree, risk level, etc. 

When using the «Risk» term as a connotation of the «Hazard» term, the probabilistic nature of potential undesirable events is considered; at the same time, the notion «Hazard» rather refers to the sources of hazard and possible consequences of undesirable events. 

Possible representations of risk as a fundamentally dualistic parameter for a single indicator in order to rank hazardous facilities in accordance with their hazard degree, which caused the use of terms such as hazard degree, hazard level, hazard class, risk index, risk level, etc., have been discussed. This is achieved by using different ranking methods, risk matrices, and risk graphs. Therefore, the «Risk» notion requires additional definitions (for example, «explosion risk index»). 

Often, the «Risk» term in phrases means probability; however, a certain undesirable event (explosion risk, risk of injuries to personnel, risk of harm to the legitimate interests of citizens) is specified.