Impregnable is one of the many English
words that bear a French ancestry, thanks to the Norman conquest of England in
1066. It derives from the Middle French verb prendre, which means "to take
or capture." Combining prendre with various prefixes has given our
language many other words, too, including surprise, reprise, and enterprise.
Remarkably, impregnable has a different origin from the similar-looking word
pregnant; that word comes from a different Latin word, praegnas, meaning
"carrying a fetus."
