From pectus to breast: anatomical and semantic gendering of the thorax

Anatomical terminology is often assumed to be structurally precise and historically stable. However, the anterior thoracic region demonstrates significant semantic transformation across time. In classical Latin, pectus referred broadly to the chest without sexual specification. In modern English, the term "breast" predominantly denotes the female mammary gland. This study investigates how a structurally stable anatomical region underwent progressive linguistic gendering. A qualitative historical-anatomical analysis was conducted integrating: (1) philological examination of classical Latin and Greek texts, including the Aeneid; (2) review of medical writings attributed to Hippocrates and Galen to assess early structural differentiation between thorax and mammary gland; (3) comparative analysis of medieval to 19th-century anatomical atlases to evaluate visual and terminological separation of thoracic and mammary structures; and (4) conceptual review of contemporary clinical framing in thoracic trauma and breast reconstruction. No human subjects were involved. Classical terminology (pectus, stēthos) denoted the anterior thorax without inherent sexual coding, while mastos specified mammary tissue. Renaissance dissection reinforced structural separation between thoracic wall and glandular appendage. Despite increasing anatomical precision, vernacular English progressively narrowed "breast" toward female mammary meaning. Modern anatomical standards maintain structural neutrality, but linguistic asymmetry persists in clinical and cultural discourse. The thorax has remained anatomically stable, whereas its linguistic representation has undergone gender-specific specialization. The transition from pectus to "breast" illustrates how anatomical regions may acquire cultural coding independent of structural change.