'aponia' originates from Greek, specifically the word 'aponía' (ἀπονία), where 'a-' meant 'without' and 'ponos' meant 'pain'.

'aponía' entered learned Modern Latin as 'aponia' and was adopted into English as a rare technical or philosophical term, preserving its Greek form.

Initially, it meant 'absence of pain' (especially bodily pain) in ancient Greek usage, and over time it has retained that core meaning in both medical and philosophical contexts.