In the Biblical story of the Tower of Babel, God foiled man’s attempt to build a tower reaching to the heavens. And the Lord said, ‘Behold, they are one people, and they have all one language; and this is only the beginning of what they will do ... Come, let us go down, and there confuse their language, that they may not understand one another’s speech’. Genesis 11: 6–7 Those familiar with the field of patient safety will recognize that confusing language does not, in fact, require divine intervention. In the space of a few years, a bewildering language of medical error and iatrogenic injury has evolved, bedeviling efforts to catalogue and understand this phenomenon. The terminology of safety is perplexing on a good day, and near impossible on a bad one. Consider a few examples of patient safety terms in common use. An ‘adverse reaction’ usually connotes an anticipated side effect of a medication or treatment. It is similar to a ‘complication’ of care. An ‘adverse event’, in contrast, signifies the presence of a medical care-related injury (anticipated or not). However, different users require different levels of harm in order to qualify an incident as an adverse event. A ‘preventable adverse event’ is an error by definition, but it is often difficult to ascertain preventability. A ‘near miss’, also called a ‘close call’, …