'heterochromatic' originates from Greek combining forms: 'hetero-' from Greek 'heteros' meaning 'other, different' and 'chromatic' from Greek 'khrōmatikos' (from 'chroma') meaning 'color'.

'heterochromatic' was formed in English from the Greek combining elements 'hetero-' + 'chromatic' (via New Latin and scientific coinage), with use appearing in scientific and descriptive contexts in the 19th century.

Initially it meant 'of different color' (different in color), and over time the term retained that core sense while also being applied in specialized fields (e.g., ophthalmology for eye-color differences and cell biology for heterochromatin).