fallible
Able to make mistakes or be wrong.
Fallible means capable of making mistakes or being wrong. Every human being is fallible: even the smartest scientists, the most experienced teachers, and the most careful students can make errors in judgment, calculation, or understanding.
When you call someone fallible, you're not insulting them. You're simply recognizing reality: people aren't perfect. A fallible doctor might misdiagnose an illness despite years of training. A fallible referee might make a bad call during a championship game. Your own fallible memory might convince you that your birthday party was on a Saturday when it was actually on a Sunday.
Understanding that everyone is fallible can help us double-check our work and think carefully before acting, since we know we can make mistakes. It can also help us forgive others (and ourselves) when mistakes happen. When your friend's fallible sense of direction leads your group the wrong way on a hike, you can laugh it off instead of getting angry.
The opposite of fallible is infallible, meaning incapable of error. Some people used to believe kings were infallible, but history proved them wrong. Today, we know that being fallible is part of being human.