supinatoextensor
/ˌs(j)uːpɪneɪtəʊɛkˈstɛnsə/Anatomy and Zoology. Now rare
adjective
Designating the supinator and extensor muscles of a limb collectively; of or relating to these muscles.
Origin
Late 19th century; earliest use found in George Murray Humphry (1820–1896), surgeon. From supinat- + -o- + extensor.