E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The Persian year consists of 365 days, so that a day is lost in four years, and the lost bits in the course of 1,460 years amount to a year. This period of 1,460 years is called a sothic period, and the reclaimed year made up of the bits is called a sothic year. (Greek, sothis, the dog-star, at whose rising it commences.)