Stupidity is rarely used in spoken English. Generally, they are stupid. In terms of severity, the most insulting tone is stupidity. The lightest and most commonly used tone is silly. \x0d\ about fools. I saw that the results of the discussion in China Overseas Chinese Forum were the same as my post. Stupidity is more serious than stupidity. But many people in China interpret it as the opposite, such as downstairs. I have never been to a foreign country. So it's hard to make a decision. The only thing that is certain is that \ x0d \ x0d \ fool, which is rarely used in spoken English, means "no brain", "lack of common sense" and "lack of judgment". For example, it is foolish to fight with his neighbor. It is foolish of him to miss such an opportunity. \ x0d \ It is foolish of you to say so. \ x0d \ x0d \ stupidity means "mental retardation" and "slow response". For example: \ x0d \ Mary made a stupid mistake. Mary made a stupid mistake. He is stupid in math. \ x0d \ Henry is too stupid to understand such a complicated problem. \ x0d \ Henry is too stupid to understand such a complicated problem. \x0d\\x0d\ In spoken English, I have never heard of someone using fool. \ x0d \ In life, you can use it on things/animals that you don't like, so you can scold stupid, that stupid dog! Use it on others, not just stupid. -stupidity is often used to laugh at yourself and say stupidity. You made a simple mistake in the exam. You can call yourself stupid. But the same thing happens to others, and it is impolite and offensive for you to say "stupid" to them. You can talk to B about people you don't like, and only use this word for people and things you don't like. \ x0d \ silly, this word should become a common word on your lips to represent "silly". I often tell children, silly girls, silly boys-when they smirk and deliberately play silly faces. \x0d\ Three years ago, before I knew the difference, I used to call my husband "stupid" with a smile, just like calling my husband "stupid" jokingly when I spoke Chinese. A couple of foreigners close to us corrected me and told me the difference. In this case, you should use silly.