Over the past decade, cancer metabolism research taught us that metabolites are much more than intermediate or end products of metabolism. As such, the name ‘oncometabolite’ emerged. Immunometabolism research has developed tremendously over the past few years and, in analogy to the cancer metabolism field, the term ‘immunometabolite’ has been used for different metabolites and purposes. Here, we propose a definition for the term ‘immunometabolite’ and provide some historical background and future perspectives on this matter. By doing so, we aim to increase interest in this fast-expanding field and to encourage further research.