Nowadays, Biophilic Design (BD) has become more well-known in architecture, without a good understanding of the term’s conceptual foundations and, therefore, its true meaning. Existing literature predominantly focuses on the characteristics and features of BD, while the historical context of its emergence is underexamined, leading to conceptual misunderstanding and a gap in the literature. This study explores the development of the term BD, primarily in the United States, from the mid-twentieth century to its formal definition in 2008 by positioning it in a broader historical and interdisciplinary context. Based on the analysis of primary and secondary literature sources, this research identifies four significant moments of collaboration between experts from different disciplines that led to BD’s formulation. Moreover, it highlights multiple influential figures throughout the emergence, most notably Stephen Kellert, who first mentioned the term BD at the beginning of the 21st century. The study shows that BD is a broad term shaped by theories in an interdisciplinary context and is, therefore, not confined to the single discipline of architecture.