'eupnoeic' originates from Greek, specifically the elements 'eu-' and 'pnoē' (or 'pnoia'), where 'eu-' meant 'good' or 'well' and 'pnoē' meant 'breath'.

'eupnoeic' developed via New Latin/medical formation from Greek elements; related forms include New Latin 'eupnoea' (British) and Classical/modernized 'eupnea' (used in English and scientific Latin), which gave rise to the English adjective 'eupnoeic' (and variant spelling 'eupneic').

Initially it literally meant 'good or well breathing' in the sense of 'healthy breathing'; over time it has retained that specific clinical meaning and now denotes 'pertaining to normal, unlabored breathing.'