The notion of trust has been traditionally investigated within many disciplines, ranging from sociology to economy, as well as politics, psychology, and philosophy. More recently, it is especially in the fields of AI, ICT, and Engineering (e.g., Critical systems), that the need for a discussion on the concept of trust, problematized in relation to the massive employment of technical artefacts in modern society, is becoming urgent. Yet, being a characteristic trait of human relationships, it is not clear whether the attitude of trust can also be directed towards artefacts. Moreover, with respect to the study of systems’ failures, the engineering sciences provide cognate notions to that of trust, e.g. reliability or dependability, which highlight our dependence on complex systems to fulfil certain tasks in a context of risk, uncertainty and vulnerability. In order to understand how far we can rely on technology, we should be able to understand, first of all, which kinds of dependencies are at stake. To this aim, in this paper, we will briefly review and discuss the main theoretical points related to trust and the technical notions mentioned, looking at both humanities and engineering literature. Then, we shall propose a preliminary ontological analysis aiming at comparing the specificities of the concepts concerned, all sharing a form of instrumental dependence.