calycanthemyn.
Etymology:  <  Greek καλυκ- calyx n.   + ἄνθεμον flower + -y suffix3.Previous versions of the OED give the stress as: calyˈcanthemy.
 Botany.
1880    A. Gray  		(ed. 6)	 400  				Calycanthemy, name of the monstrosity in which the calyx imitates an exterior corolla.
 This entry has not yet been fully updated (first published 1888; most recently modified version published online June 2019).