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 now 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.” Although I rarely side with British English habits, I have long felt the opposite: autumn, with only one definition, carries with its muted sound an auditory beauty that better matches the mood and weather of the quiet season than the protean fall.