Based on the appearance of the term within the academic literature, it would appear that transdisciplinarity (TD) approaches are receiving increased research attention. However, the literature suggests a lack of consensus over how TD is defined and classified. This could give rise to inconsistency and papers that claim to be TD which are not, and alternatively papers that fail to mention TD but which might be classified as such. This is significant and creates a challenge in identifying the true level of TD research. This work contributes towards understanding the state of TD within engineering. Explicitly, we address the research question: Is the engineering academic literature claiming to be TD, actually TD? Within this study we operationalise the work of Jantsch and use this as a means to classify the disciplinarity of 177 engineering journal papers which reference TD within their abstract. The results show only 24% to be TD. The majority (64%) are classified as interdisciplinary. Conclusions find that to improve consistency, a clear definition and rules for differentiation between TD and ID research are required. Future work calls for: (1) comparative studies which apply different methods for assessing disciplinarity across the dataset used within this study and which use the method employed within this study across different fields. (2) Research to analyse whether TD working is being undertaken in engineering without it being referenced within the paper.