A new season arrives on Friday, but what should we call it? Unlike the others, the third has two names.Autumn seems fancier and more formal, and has antiquity on its side. It's from a Latin word whose root may have meant "to satisfy oneself." Autumn is, indeed, the season of harvest when a cornucopia of food is available.Fall seems more colloquial. Some say it's a shortening of "fall of the year" in the sense of the waning of the year in its last months. Others say it simply reflects the season in which the leaves fall from the trees.Fall is also an aberrant name. Spring, summer, autumn, and winter all have six letters. Fall has only four.So if you're a conformist, stick with autumn. If you're a freethinker, favor fall.