Teetotalism is the noun for the practice or the principle of never drinking alcohol at all. Where 'teetotal' describes a person and 'teetotaller' names one, teetotalism names the whole idea — the belief, the movement, the way of living. It is uncountable, and it is a formal, bookish word: you meet it in history writing, in articles about religion or public health, in sentences like 'Teetotalism spread rapidly through the industrial towns' or 'Her teetotalism was a matter of religious conviction.' Nobody says it at a dinner table. The word carries its history with it. It belongs above all to the nineteenth-century temperance movement in Britain and America, where organised campaigners urged people to sign a pledge of total abstinence; so when you read 'teetotalism' you are usually reading about a social movement with meetings and pledges and moral argument, not simply about one person's private choice. That is the difference from 'not drinking': teetotalism sounds like a position you hold, something you could argue for. If you just mean a person's habit, 'he doesn't drink' is the natural English.

禁酒主義、絕對戒酒（作為一種主張或風氣，不是單純某人不喝酒）。書面用語，常出現在談十九世紀禁酒運動的文章裡。