Mid 17th century (in an earlier sense). From classical Latin plex-, past participial stem of plectere to plait, interweave + -ure, perhaps after flexure.
Definition of plexure in US English:
plexure
nounˈplɛkʃə
Biology= "plexus". Now rare.
Origin
Mid 17th century (in an earlier sense). From classical Latin plex-, past participial stem of plectere to plait, interweave + -ure, perhaps after flexure.