'angular-veined' is a compound of 'angular' and 'veined'. 'Angular' originates from Latin, specifically the word 'angularis', where 'angulus' meant 'angle'. 'Veined' comes from Old French 'veine' ultimately from Latin 'vena', where 'vena' meant 'vein' or 'blood-vessel'.

'angular' passed into English via Old French 'angulaire' and Middle English forms before becoming modern English 'angular'. 'Vein' entered English from Old French 'veine', derived from Latin 'vena'. The compound 'angular-veined' is a productive descriptive compound formed in modern English by combining these elements.

Individually the elements meant 'relating to an angle' and 'a blood-vessel or a streak/vein in plants or minerals'; over time the compound came to mean specifically 'having veins that form noticeable angles' in contexts like botany or description of patterns.