'apneic' originates from Greek, specifically the word 'ápnoia' (Greek ἄπνοια), where 'a-' meant 'without' and 'pnoē' meant 'breathing'.

'apneic' developed via New/Modern Latin 'apnoea' (and English 'apnea'/'apnoea'), with the adjective formed by adding the suffix '-ic' to the noun; the modern English adjective 'apneic' comes from 'apnea' + '-ic'.

Initially it meant 'without breath' (literally), but over time it evolved into the medical sense 'temporary cessation of breathing' and the adjectival sense 'relating to apnea'.