The term ‘soil science’ remains inadequately defined, despite numerous definitions of soil itself. While it is commonly understood as the scientific study of soil, the adjective ‘scientific’ typically denotes a systematic, methodological approach grounded in falsifiable principles. However, few attempts have been made to formally define the discipline of soil science itself. This paper proposes an integrated definition, aligning with contemporary perspectives that view soil not as a discrete entity but as a dynamic component of the Earth system. Our definition is: “Soil science is the study of the soil of the Earth and other planets, using evolving theories and knowledge to understand its role in sustaining ecosystem functioning, tackling environmental challenges, and supporting humanity.”