The terminal part or hind segment of the body in certain invertebrates.
- ‘The pygidium, like the cephalon, was a structure in which segments were fused together.’
- ‘As noted above, it closely resembles the syntype pygidium of E. acadicus, and is tentatively assigned to that species.’
- ‘A pygidium with an attached thoracic segment represents a meraspid stage of the species.’
- ‘By contrast, some representatives of the Olenelloidea have pygidia with multiple segments.’
- ‘The post-segmental posterior terminus is called the pygidium.’
Mid 19th century: modern Latin, from Greek pugē rump.