suprafacial
/ˌsuːprəˈfeɪʃl/ /ˌsjuːprəˈfeɪʃl/adjective
1 Anatomy and Zoology. Located above the face or the facial nerve.
2 Chemistry. Of a pericyclic reaction undergone by a molecule: involving the formation of two new bonds on the same face of the molecule. Opposed to antarafacial.
Origin
Late 19th century. From supra- + facial.