查字典有固定的三种表达：

look sth up in the dictionary

consult a dictionary

refer to a dictionary

如：

If you don't know a word, you can look it up in a dictionary.

如果你有不识的字，可以查字典。

You can look the word up in the dictionary. 你可以在词典里查这个词。

Is that the correct spelling?

I don’t know—look it up in a dictionary.  

那是正确的拼写吗？

我不知道——查查词典吧。

I refer to the dictionary frequently. 我经常查阅词典。

Why grope after the meaning of a word? Refer to the dictionary!

何必苦苦思考这个词的意思？查字典吧！

If you have no idea about it, consult a dictionary, please.

如果你不知道这是什么意思，可以查查字典。