Healthcare has experienced rapid transformation with the development of digital technologies which aim to make healthcare safer and more efficient. In response, health informatics has evolved, including nursing informatics, which integrates nursing, information and communication technologies (ICT) and professional knowledge to improve patient outcomes. New language has developed to describe informatics and its processes; however, this has generally been poorly understood. This paper will describe current definitions of nursing informatics from three different healthcare contexts: Australia, the United States of America and Canada, to identify the similarities and differences between these definitions and to summarise the distinct bodies of knowledge described by each country. These countries have amongst the oldest definition attempts in the literature. A pragmatic approach was taken in this narrative review, working forward from historic references and backwards from recent references extracted from published health and nursing informatics literature.