倘若 / 假若 / 设若【tǎngruò / jiǎruò / shèruò】

倘若 means "if" in written Chinese. It opens the condition, and the result clause often starts with 就, 便 or 则. It leans towards situations the writer treats as hypothetical or contrary to fact.

It can also follow the subject.

假若 and 设若

假若 is interchangeable with 倘若. 设若 – literally "set up an if" – is rarer, and sets up an argument or a thought experiment.

倘 on its own and 倘使 mean the same and sound older still.

Not "even if"

倘若 sets a condition the result depends on. When the result holds whatever happens, the word is 即使.

• × 倘若下雨，比赛也照常进行 → 即使下雨，比赛也照常进行

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In conversation 倘若 sounds bookish; 如果 or 要是 do the job there. 假如 sits between the two and has its own point.