To understate something is to describe it as smaller, less serious, or less important than it truly is. It is a verb about the size of your words compared with the size of the facts. It works two very different ways, and students should feel the difference. First, as a fault or a dodge: a company understates its losses, a government understates the number of deaths, a report understates the risk. Here it shades toward hiding the truth, though it is gentler than 'lie' — it suggests shrinking rather than inventing. Second, as a skill: a writer or speaker deliberately says less than the case deserves, and the smallness of the words makes the point land harder. British English is famous for this — calling a terrible storm 'a bit of weather'. Two set phrases are worth memorising because they are very common. 'To say the least' and, above all, 'it would be an understatement to say...' — and the near-formulaic 'To say he was angry would be an understatement', meaning he was furious. The related noun is understatement; the adjective is understated. You can also understate your own case, your qualifications, or your feelings, which can be modesty or can be a tactic.

輕描淡寫、說得比實際輕（刻意把事情講小；名詞 understatement 常譯「輕描淡寫的說法」）