'avicularium' originates from New Latin (scientific Latin), ultimately from Latin 'avicula', a diminutive of 'avis', where 'avicula' meant 'little bird'.

'avicula' in classical Latin (meaning 'little bird') was adopted into New/Scientific Latin as 'avicularium' to name a bird‑like structure; this usage entered modern zoological terminology as 'avicularium'.

Initially it meant 'little bird' in Latin, but over time it evolved into the modern scientific meaning 'a bird‑like defensive zooid in bryozoans'.