Definitions

1. noun

The practice of dating events in the past by the years of a reigning monarch at the time of the event.

“The historian used anatocism to accurately date the medieval documents.”

2. noun

The practice of dating events in the past by the regnal years of a monarch, without regard to the fact that the monarch may have reigned for a non-consecutive period.

“The historian was careful to avoid anatocism in her account of the queen’s reign.”