在英文中，户外活动可以称为"outdoor activities"。这个短语来源于英语中的两个单词"outdoor"和"activity"。"Outdoor"指的是户外的，而"activity"指的是活动。因此，将两个单词结合起来，就可以表示户外活动的意思。

下面是一些关于户外活动的英文例句：

I love going hiking and camping on the weekends. It's a great way to escape the city and enjoy some outdoor activities.

My parents used to take us on outdoor adventures when we were kids. We would go fishing, biking, and even rock climbing.

There are many different types of outdoor activities that you can try, depending on your interests and physical abilities. Some examples include hiking, biking, camping, fishing, and kayaking.

If you want to stay healthy and active, it's important to incorporate some outdoor activities into your routine. Whether it's going for a walk or jog, playing sports, or just spending time in nature, there are plenty of ways to enjoy the great outdoors.