But ironically, the term 'football' actually came from the fact that the game was played on foot, as opposed to on horseback...and soccer came from British slang. See, what we call football/soccer wasn't the
only game played on foot. You had rugby football, association football, etc. Rugby football was often shortened to 'rugger' and 'association football' to 'soccer', because I guess 'asser' doesn't have quite the same ring to it. Eventually they sorted things out as 'rugby' and 'football', but we already
had a 'football', so we stuck with 'soccer' (as did Australia, who also have their own football).
http://www.theatlantic.com/international/archive/2014/06/why-we-call-soccer-soccer/372771/
But yeah, for units and dates we're totally whacked.