calendar - a system of timekeeping that defines the beginning and length and divisions of the year

Hebrew calendar, Jewish calendar - (Judaism) the calendar used by the Jews; dates from 3761 BC (the assumed date of the creation of the world); a lunar year of 354 days is adjusted to the solar year by periodic leap years

Hindu calendar - the lunisolar calendar governing the religious life of Hindus; an extra month is inserted after every month in which there are two new moons (once every three years)