'equiangular' originates from Latin, specifically the elements 'aequus' meaning 'equal' and 'angulus' meaning 'angle'.

'equiangular' was formed in English by combining the Latin-derived prefix 'equi-' (from 'aequus') with the adjective 'angular' (from Latin 'angulus'); the construction reflects New Latin/Modern English formation and became established in technical geometric usage as 'equiangular'.

Initially, it meant 'having equal angles', and over time it has retained this specialized geometric meaning in modern usage.