Wordia - The Definition Of Season

noun, one of the four equal periods into which the year is divided by the equinoxes and solstices, resulting from the apparent movement of the sun north and south of the equator during the course of the earth's orbit around it. These periods (spring, summer, autumn, and winter) have their characteristic weather conditions in different regions, and occur at opposite times of the year in the N and S hemispheres

From Collins

©HarperCollins 2008. Collins English Dictionary definition of season