to make someone worried, unhappy, or angry

It still upsets him when he thinks about the accident. 一想起那次事故他仍很恼火。

Don't upset yourself by thinking about what might have been. 别再去想原本可能会怎样了，何必自寻烦恼。

to change the usual or expected state or order of something, especially in a way that stops it from happening or working

Any mechanical problems would upset our plans of driving across the desert. 哪怕是很小的机械故障都有可能搅乱我们驾车穿越沙漠的计划。

to push or knock something out of its usual position, usually by accident, especially causing it to fall

Our dog upset the picnic table, spilling food everywhere. 狗撞翻了野餐桌，把我们的食物弄得到处都是。

to make someone feel slightly sick

He can't eat grapes - they upset him/his stomach. 他不能吃葡萄——他的胃受不了。

upset the apple cartidiom 制造麻烦；（尤指）打乱计划

worried, unhappy, or angry

Don't get upset about the dress - there's only a little stain on it. 不要为这条裙子难过了——上面只有一个小污点而已。

[ + to infinitive ] She was very upset to hear that the party had been cancelled. 听说聚会取消了，她很沮丧。

[ + that ] He was very upset that you didn't reply to his emails. 你没给他回信，他很失望。

If you have an upset stomach you feel slightly ill, especially because of something you have eaten or drunk.

I have an upset stomach/tummy - serves me right for eating so much. 我肚子不舒服——我这是自作自受，谁让自己吃得太多。

confusion and problems

How much upset will the new monitoring procedures cause? 新的监控程序将会带来多大的混乱?

an occasion when someone beats the team or player that was expected to win

It would be quite an upset if the favourite didn't win. 如果这个夺标大热门没有获胜，那就真是一个大冷门。

a slight illness of the stomach

Melanie has a stomach/tummy upset so she won't be going to school today. 梅兰妮肚子不舒服，所以今天不去上学了。