'annelidic' originates from New Latin, specifically the word 'Annelida', where Latin 'anellus' meant 'little ring' (diminutive of 'annulus', 'ring').

'annelidic' changed from New Latin 'Annelida' (the group name for segmented worms) to the English noun 'annelid', and eventually formed the modern adjective 'annelidic' by adding the suffix '-ic'.

Initially it referred to the ringed or segmented creatures themselves (Annelida); over time the derived adjective came to mean 'relating to annelids' in general scientific usage.