Speaking about security we use lots of terms but, probably, we are forgetting the true meaning of thoose terms.
I found and interesting article by David E. Stern that tries to answer to the question “What are vulnerabilities?”
Lets look at a few traditional vulnerabilities. The strongest castles became vulnerable to intrusion with the introduction of modern artillery; big enough guns destroy the biggest walls. Early wild west stage coaches were easy targets for large groups of bandits because of their limitations in armor, speed, and defensive weaponry. Humans, without the benefit of vaccinations fall victim to viruses and bacteria because their vulnerable bodies simply can’t fight back.
This is 1 of 3 part article.