'orthopyroxene' originates from Greek, combining the prefix 'ortho-' (Greek 'orthos') meaning 'straight' or 'correct' and 'pyroxene' from Greek 'pyroxenos', where 'pyro-' meant 'fire' and 'xenos' meant 'stranger/guest'.

'pyroxene' entered scientific usage via New Latin/German in the late 18th century from Greek 'pyroxenos'. The compound 'orthopyroxene' was later coined in mineralogical literature (19th century) to distinguish orthorhombic pyroxenes (e.g., enstatite) from clinopyroxenes.

Initially, 'pyroxene' emphasized the association with volcanic ('fire') rocks; over time the term was formalized to name a mineral group, and 'orthopyroxene' came to mean specifically the orthorhombic subgroup of pyroxenes.