There are several key words used throughout various industries when relating information important to safety. Modern safety practitioners may be unaware of the meaning these words have and the perception of them in the general public. The Engineering Council has suggested that public perception eventually results in regulation, in media treatment and in government decisions affecting industry. So it is vitally important that the engineering profession understands the impact it can have by using words such as risk, danger, safety, probability and chance. This paper presents the findings of public perception research into the meanings of these words and traces their actual historical meanings.