'asterial' originates from New Latin, specifically the element 'aster-' from Greek 'astḗr', where 'astḗr' meant 'star', combined with the Latin suffix '-alis' meaning 'pertaining to'.

'aster-' (Greek 'astḗr') passed into Latin as 'aster' and was used in New Latin formations; the adjective-forming suffix '-alis' produced forms like 'asteralis', which in English yielded the adjective 'asterial'.

Initially it meant 'pertaining to stars' (literal star-related sense), but over time it has been applied in botany and morphology to mean 'pertaining to Aster (the plant) or star-shaped'.