unpenetrable vs impenetrable
The book was so difficult to read and full of complex ideas, that it was totally unpenetrable or impenetrable .
I wrote unpenetrable but it was corrected on the latter word.

What is the difference?
I looked through the dictionary. There are two vaeiant forms.

Thanks in advance.

Question

unpenetrable  vs impenetrable
The book was so difficult to read and full of complex ideas, that it was totally  unpenetrable  or impenetrable .
I wrote unpenetrable but it was corrected on the latter word.

What is the difference?
I looked through the dictionary. There are two vaeiant forms.

Thanks in advance.

Answer

If 'unpenetrable' exists it must be very rarely used. I've never heard it, and it's not in any of my dictionaries. It's possible that it is being used because as a misspelling, because it's fairly easy to see the logic behind it, and so maybe over time it will come to be recognised as a possible variant - but for now I would suggest sticking with 'impenetrable'

Answer

The meaning is the same but the first word is rarely used.

Answer

Hi,
Unpenetrable isn't a word in common use, you will almost always see impenetrable used.
To be honest it's a word I've never used or come across in day to day language.

Hope this helps