恐龙的英文是 "dinosaur"。

这个词来源于希腊语，它由两个词组成："deinos"，意为"可怕的"或"巨大的"；"sauros"，意为"蜥蜴"。因此，恐龙的英文就是指"可怕的蜥蜴"。

下面是一些英文例句：

I went to a museum and saw a lot of interesting dinosaur fossils.
I'm reading a book about dinosaurs right now. It's really fascinating.
Some people think that dinosaurs were warm-blooded, while others think they were cold-blooded.

以下是这些例句的中文翻译：

我去了一家博物馆，看到了许多有趣的恐龙化石。
我现在正在读一本关于恐龙的书。这真是太迷人了。
有些人认为恐龙是温血动物，而有些人认为它们是冷血动物。