I want to make a sort of link, but it isn't really a link. If I hover over (or click) a certain word, I want this to change to another word. When I don't hover, (or click again), the word will change back. But I want my current css to stay for other things...

Do you mean for example..?:

Like this:

(I'm holding my cursor over this link):

Link 1 (as I hold cursor on link 1, Link 2 turns blue) Link 2

Do you mean like that?

she means, on mouse over, the word that is being moused over changes to another word, and on mouse out, the word changes back.

Try this
<p id="mytext"
onmouseout="mytext.innerText='First word';"
onmouseover="mytext.innerText='Second word';">
First word
</p>

Try this
<p id="mytext"
onmouseout="mytext.innerText='First word';"
onmouseover="mytext.innerText='Second word';">
First word
</p>
Thx ! But that doesn't work in Mozilla Firefox... Is there any way this could work in Firefox too?