merohedral
/ˌmɛrə(ʊ)ˈhiːdr(ə)l/Crystallography
adjective
Of a crystal or crystal form: having one half, a quarter, or one eighth of the maximum number of faces possible for its crystal class; merosymmetric.
Origin
Late 19th century; earliest use found in Nevil Story-Maskelyne (1823–1911), mineralogist. From mero- + -hedral.