Originally called harvest, the season between summer and winter became known as both autumn and fall (from fall of the leaf, opposite spring of the leaf) around the late fifteenth to early sixteenth century, respectively. While fall is slightly more common in American English, autumn dominates in British English.
H.W. Fowler preferred the American term, calling it, in The King’s English, “better on the merits than autumn, in every way: it is short, Saxon (like the other three season names), picturesque: it reveals its derivation to every one who uses it, not to the scholar only, like autumn.” But I have long thought the opposite: autumn, with only one definition, carries an auditory beauty with its muted pronunciation, which matches the mood and weather of the season.