'arthral' originates from Greek, specifically the word 'arthron', where the root 'arthr-' meant 'joint'.

'arthron' passed into New Latin/medical Latin as forms such as 'arthralis' and then into English medical usage as 'arthral' (by shortening and adaptation from these classical-medical forms).

Initially it was strictly a combining/formative element meaning 'joint', but over time it came to be used as a standalone adjective or noun referring to 'relating to joints' or 'joint pain'.