monocephaly
/ˌmɒnə(ʊ)ˈsɛfəli/ /ˌmɒnə(ʊ)ˈsɛf(ə)li/ /ˌmɒnə(ʊ)ˈkɛfəli/rare
noun
Botany. The condition of being monocephalic or monocephalous.
Origin
Late 19th century (in an earlier sense). From mono- + -cephaly, after monocephalic, monocephalous, monocephalus.