The New Oxford American Dictionary reports that the origin of the word soccer is a shortening of association football. I have been used to say American football to mean the sport played in America, and soccer to mean the sport where only a player can touch the ball with his hands.

There are many theories about the origin of OK. The more recent I have heard is that it originated as 0K (zero K); the dictionary I use most of the time says that its origin is fro "orl korrect", humorous form of all correct, popularized as a slogan during President Van Buren's reelection campaign of 1840.

It's funny that the first example is the answer they taught me when I started to study English as second language.