"Soccer" was a term first used in Britain long ago--they switched to "football", we just kept the old term. "Football" (US) probably comes because the game developed from rugby football.
Also, there used to be a lot more kicking in early football. As the passing game into vogue the shape of the ball even changed to make it easier to throw as opposed to kicking it.
Hmm... I guess because the game starts with kicking the ball, and it's also how you get field goals... I can't explain away the soccer term though.
To confuse the foreigners?
I call it futbol