Caligulismn.
Etymology: < Caligula, cognomen of the third Roman Emperor + -ism suffix.Previous versions of the OED give the stress as: Caˈligulism.
1745 H. Walpole (ed. 2) II. 103 Alas! it would be endless to tell you all his Caligulisms.
This entry has not yet been fully updated (first published 1888; most recently modified version published online September 2019).