'nonisotropic' originates from English, specifically formed from the prefix 'non-' (meaning 'not') and the word 'isotropic', where 'isotropic' itself comes from Greek 'isos' meaning 'equal' and 'tropos' meaning 'turn' or 'direction'.

'isotropic' entered English via New Latin and Greek (from Greek 'isotropos'); the negated form 'nonisotropic' was formed in modern English by adding the prefix 'non-' to 'isotropic' to indicate the opposite.

Initially, the root 'isotropic' described 'equal in all directions'; 'nonisotropic' has maintained the straightforward negated meaning of 'not equal in all directions' (i.e., direction-dependent properties).