The concept of sustainability has often been used in both research on OA publishing systems, and as a desirable design principle in thinking of and building any future OA publishing business model. At the same time, the term has gained considerable attention across other domains, mainly in relation to environmental sustainability or sustainable development (especially with the UN’s Sustainable Development Goals, SDGs), which makes it even more important to draw a clear demarcation line between such uses. Despite its social importance, the financial and resource-related sustainability of OA publishing hasn’t been clearly defined and largely differs across countries. The presentation is aimed at formulating questions that could lead us to gaining transparency and reaching a consensus on the way the term ‘sustainability’ will be used henceforth, especially in the theoretical and practical research of funding OA publishing (diamond OA in particular). It outlines some of the results of discussing this issue within the DIAMAS project with European OA publishers, learned societies, advocacy organisations and researchers. One of the first obstacles in reaching a better understanding is crossing the linguistic barrier and acknowledging that the term has not always gained equal traction across countries and when used, it has multiple connotations in all languages. The span of meanings could range from simply being durable and existing in the long term, or to enduring without having negative implications for other aspects of the ecosystem, such as depleting resources others might need or affecting their survival. It is also important to acknowledge the fact that stakeholders involved in OA publishing vary and therefore perceive sustainability (and the ways to achieve it) in different ways: we often witness strategies such as more successful fundraising, efficient use of resources or shared resources, or cost reduction measures. While sustainability goals may range from cost recovery only, to enabling reinvestment or guarding against ‘hard times’, or sustaining revenues ‘at the same level’ - even if that includes high profit margins or companies with shareholders. The building blocks of the scope and meaning of ‘sustainability’ have evolved from answering questions on the object or unit of sustainability (What is sustainable? Is it a journal, a publisher, a business model or a wider publishing ecosystem?) as well as on the sustainability actors or players (Who is a sustainer? Who holds responsibility for sustainability? Which stakeholder/group of stakeholders?). A conclusion that emerged suggests that a univocal and obvious definition of ‘sustainability’ is unlikely to be achieved as it is dependent on multiple perspectives of actors in the ecosystem and is necessarily involving dynamics and transformative practices. In short, this presentation hopes to give the audience a deeper understanding of what sustaining OA publishing means in different contexts. It will encourage listeners to question their perceptions of sustainability before possibly coming to new conclusions to address the topic more thoroughly in their local contexts, and to consider how we collectively take steps towards more unified terms and definitions.