This article explores the developing definition of moral injury within the current key literature. Building on the previous literature regarding 'Moral Injury, Spiritual Care and the role of Chaplains' (Carey et al. in JORH 55(4):1218-1245, 2016b. doi: 10.1007/s10943-016-0231-x ), this article notes the complexity that has developed due to definitional variations regarding moral injury-particularly with respect to the concepts of 'betrayal' and 'spirituality'. Given the increasing recognition of moral injury and noting the relevance and importance of utilizing a bio-psycho-social-spiritual model, this article argues that betrayal and spirituality should be core components for understanding, defining and addressing moral injury. It also supports the role of chaplains being involved in the holistic care and rehabilitation of those affected by moral injury.