A guihai year is the last in the stem-and-branch count of years; after it, the count starts again from jiazi.
Tips
culture
癸 is the tenth and last Heavenly Stem and 亥 the twelfth and last Earthly Branch, so their pair closes the cycle that runs 从甲子到癸亥 'from jiazi to guihai'. Every guihai year is a Year of the Pig.
