"Err" comes from the Latin word "errare,” meaning “to stray or wander.” Related words, such as errant and erroneous, have the same Latin origin.

But the noun form of “err,” error, appears in many American English expressions.

For example, human error is often the reason police give for a preventable – but unplanned – accident. If a train crashes because the driver fell asleep, that crash was caused by human error.

But some errors or mistakes are nobody's fault directly.

Let's say a plane crashes. An investigation proves that the crash was caused by an undetectable engine problem. There was nothing the pilot could have done differently to prevent the crash. In this case, the cause of the crash was not pilot error.

But that is enough talk about crashes.

Let's say this pilot is on the runway preparing to take off. Suddenly, a bad storm begins. She could take off but decides to wait until the storm passes. We could say she wants to err on the side of caution. This simply means that of all the options available, you choose the safest one.

If you feel sick one day but feel fine the next, you may err on the side of caution and stay home from work.

You can err on the side of other things. For example, let's say your child's school asks for a money donation to build a new playground. You don't know how much other parents are giving. So, you err on the side of generosity and give more than you think is expected.

Here's another example. If a person has treated you badly in the past, you can err on the side of being polite to them.

Acting politely is the right thing to do. And it's good for another reason, as well. When you are nice to people who have treated you badly in the past, they may re-think their bad behavior. They may see the error of their ways.

We often use this phrase when we want to say that a person has realized the things they have done wrong. But be warned – we don’t use this phrase lightly. The "error" in this expression is usually a serious problem with a person's character or behavior that may cause trouble.

This expression also means the person became aware and then fixed the problem.

Let's go back to the pilot.

Imagine she had a bad habit of working too hard. She would lie about her long flight assignments so that she could fly even more routes. However, one day she realized that she was putting the passengers in danger. She saw the error of her ways and stopped.

If her supervisor had caught her and forced her to change her work habits, you would not use this expression. And you would not say the supervisor saw the error in her ways. It is always a self-discovery.

Now, talking about self-discovery brings us to scientific discoveries.

Scientists are very careful people, but scientific research is full of errors. Scientists know this. So, they sometimes say that their findings have a margin of error. That margin, or amount, shows how accurate they think their answer really is.

You can also add prepositions to this expression. For example, if something is unlikely to happen based on information you have collected about it, it is outside the margin of error. If it is likely to happen, it is within the margin of error.

Another scientific term that we use in any part of our lives is trial and error. Trial and error means you find the best way to do something by trying many ways and getting rid of the ways that failed.

divine – adj. of, relating to, or proceeding directly from God
stick – v. to remain in a place, situation, or environment
error – n. something that is not correct : a wrong action or statement
errant – adj. straying outside the proper path or bounds : behaving wrongly
erroneous – adj. not correct
undetectable – adj. impossible to discover or notice
caution– n. care taken to avoid danger or risk : a careful attitude or way of behaving
generosity – n. the quality of being kind, understanding, and not selfish : the quality of being generous
polite – adj. having or showing good manners or respect for other people