Teetotalism is a noun, meaning staying away from alcohol. If you see someone drinking a soda at a bar, he might practice teetotalism or he might just be planning to drive himself home.
Since drinking alcohol is generally an accepted practice now, the word teetotalism has fallen out of common use. You might think the groups promoting teetotalism in the United States in the 1920s succeeded when laws were passed prohibiting alcohol (effective from 1920 to 1933). However, you would be wrong, because with the Prohibition era came underground bars and homemade moonshine.