- (rare) In such a way as to be an accessory; in an auxiliary manner, additionally.
- 1869, CI Hemans, A History of Mediaeval Christianity and Sacred Art in Italy, page 463:
- Besides these groups are introduced, accessorially, all the Fathers and Doctors whose writings maintain the Roman Church's doctrine of the Real Presence.
- 1916, AJ Beveridge, The Life of John Marshall, volume 3, page 625:
- English books unite in declaring that he, who councels, procures or aids treason, is guilty accessorially and solely in virtue of the common law principle [...].