Of the many pairs of confusing words, just and only is among the most common. This is because in one use, the words are synonyms; and in other uses, they mean completely different things. For example:
I am just trying to give an example.
I am only trying to give an example.
Here the two sentences mean the same thing because the words just and only mean the same thing – merely. In this case, the two words are synonyms.
Now look at these examples:
This example is just perfect.
This is the only example.
Here just and only mean two different things. In the first sentence, just means exactly; and in the second, only means unique or there is no other. Since the two words here have different meanings, they cannot be interchanged.
Other uses of just:
I just arrived. (meaning very recently)
I was just about to leave. (meaning right at that very moment)
The school is just in front of the house. (meaning a short distance from).
She is a just teacher. (meaning fair)
Other uses of only:
This movie is only for adults. (meaning exclusively)
This book is not only good, but informative as well. (meaning having more qualities)
If only I could go. (meaning wish)
In these two sets of examples, just and only cannot be interchanged because they all have different meanings.
So, what do all these cases tell us? They tell us that just and only are interchangeable in “just” one case – when the two mean merely. In all other cases, when they have various other meanings, the two cannot be interchanged. If this point is kept in mind, there can be no cause of confusion.
Do you know of any other uses of just and only?