Septennial
December 9, 2025
Septennial means something that happens every seven years or lasts seven years, and this glossary explains its meaning, history, use, and related time words.
Septennial means something that happens every seven years or lasts seven years, and this glossary explains its meaning, history, use, and related time words.
A fortnight is a time unit equal to two weeks, useful for understanding dates, pay periods, and schedules in many English speaking countries.
A sidereal second is a time unit based on Earth turning once relative to the stars, and it is slightly shorter than the normal second used in everyday life.
A sidereal minute is a time unit used in astronomy, based on Earth spinning once relative to the stars, and is slightly shorter than a normal minute.
A sidereal hour is a time unit used in astronomy that is slightly shorter than a normal hour and is based on Earth spinning once relative to distant stars.
A sidereal day is the time Earth needs to turn once in relation to distant stars, a bit less than 24 hours, and it is very important in astronomy.
A sidereal year is how long Earth takes to go once around the Sun compared with the distant stars, used mainly in astronomy to measure true orbits.
A tropical year is the time Earth takes to go from one spring season back to the next, about 365.24 days, and it is used to keep our calendars matching the seasons.
A leap year is a special year with one extra day so our calendar stays in step with the seasons and the movement of Earth around the Sun.
A Julian year is a fixed time unit equal to exactly 365.25 days that astronomers use to measure long periods in a clear and simple way.