Method to highlight any cell that contains anything but 'allowed' set of words

Hi all,

For a linguistic project at university I'm looking for a way to do the following:
I have a data set containing text (no numbers) that spans several columns and rows. I have a list of 'allowed' words (about 100 words) that can be in these cells. If a cell contains a sentence with a word that is anything other than these allowed words it should be somehow marked. Ideally the 'wrong' word itself is marked, but it would already be very helpful if the cell that contains the word is marked in some way.
I tried conditional formatting, but it seems to only allow formatting cells that contain a certain word, not if it doesn't contain certain words. Is there a function or a script that would be able to do this? Thanks in advance!

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Simplified example:

Say you have four allowed words:
Apple
Pear
Orange
Banana

You have the following cells:

>Apple Banana
>Pear Pear Orange Pear
>Banana Apple Orange Kiwi

The third cell should be marked because it contains a word outside of the set.

This is great, thanks so much!

It works very well, but if you have a little bit more time, I have one more question: is there a way for the macro to ignore punctation marks like , . : ; etc.? Now if there is for instance a comma after a word, it will see that as part of the word and mark it red even if it is one of the allowed words. (e.g. "banana," is marked red) I can add all the possible permutations with different punctuations but maybe there is a simpler way.
But thanks either way!!

Superb!
Building on your code I added two lines to catch any special characters in front of text, like "(banana", and words that are completely between special characters, like "(banana)"
Not it works perfectly! Thanks again.