Tropical year
WordNet
noun
(1) The time for the earth to make one revolution around the sun, measured between two vernal equinoxes
WiktionaryText
Noun
tropical year
- The time that it takes for the Sun to return to the same position along the ecliptic, as viewed from the Earth, especially:
- A vernal equinox year, the time between two successive vernal equinoxes.
Usage notes
The vernal equinox tropical year of about 365.2424 years (varying over the centuries) is used for the Gregorian as well as earlier calendars, to keep the vernal equinox as close as possible to March 21st. This is different from the mean tropical year of 365.24219 days.