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

'arthrous' was formed in English from New Latin/Modern scientific usage based on Greek 'arthron' (joint) + the English adjectival suffix '-ous', passing through Medieval/Neo-Latin scientific vocabulary before becoming an English technical adjective.

Initially derived to mean 'pertaining to joints' in technical anatomical contexts, and it has retained that specialized meaning in modern biological usage.