'annular' originates from Latin, specifically the adjective 'annularis', where the root 'annulus' meant 'ring'.

'annular' passed into Late Latin as 'annularis' and then into English (via scientific and scholarly Latin usage) as 'annular'; 'annularness' is a later English nominalization formed by adding the suffix '-ness' to 'annular'.

Initially it meant 'ring-shaped' in Latin and early scientific use; over time the base meaning has been retained, and 'annularness' specifically denotes the state or quality of being ring-shaped.