While the notion of degrowth has gained traction in recent times, scholarship on degrowth transformations has yet to provide a conceptualisation that captures key attributes of what such transformations entail: (1) the reduction of some items and the expansion of others and (2) profound changes in various dimensions of social being, including in how humans interact with nature, non-humans, and one another, changes in social structures and changes in how we are as human beings. The present paper develops a comprehensive and non-reductionist conceptualisation of degrowth, understanding it to involve deep transformations on four interrelated planes of social being: material transactions with nature, social interactions between persons, social structure, and people's inner being. On each plane, these transformations consist in reducing, and ultimately absenting, some currently existing items while expanding others. The paper considers the implications of the conceptualisation for degrowth practice and theorising, focusing on top-down eco-social policies, bottom-up initiatives and self-transformation. It is found that degrowth would benefit from considering more seriously the effects of policies and initiatives across all four planes and from acknowledging diversity on each plane. Moreover, it is concluded that more attention should be paid to the plane of peoples' inner being.