Complex sentence: During a Sothic cycle, the 365-day year loses enough time that the start of the year once again coincides with the heliacal rising of the star Sirius, called Sothis in Greek; a single year between heliacal risings of Sothis is a Sothic year.
Split into simpler sentences: During a Sothic cycle, the 365-day year loses enough time that the start of the year once again coincides with the heliacal rising of the star Sirius, called Sothis in Greek. A single year between heliacal risings of Sothis is a Sothic year.