Today, we will talk about the word "smart." Like many words, "smart" has lots of different meanings, depending on how and when you use it.

For example, “smart" can describe someone who is very neat-looking. A person wearing an official uniform with shiny shoes and buttons can look very smart.

We can also use "smart” as a verb. Used this way, it means “to feel pain.” That pain could be physical or emotional.

So, if you hit your thumb with a hammer by accident, you might yell out, "Ow, that smarts!" This would be a very polite thing to yell when you experience extreme physical pain. Many of us probably wouldn’t be that polite. We would probably yell something quite different.

Okay, so that’s the physical part. But a hurtful comment or remark can also smart. Those hurt in an emotional way.

In another use of the word, we add "smart" to the names of devices and tools. This means that they are enabled by computers -- like a smartphone.

But, by far, the most common definition of "smart" is to be very good at learning and understanding things. So, when students do well at school and get good grades, we can call them “smart.”

Being smart, however, goes beyond the classroom. People can be smart in different ways.

If you have attended school for many years and have many degrees, people might call you book-smart. Book-smart people are well-read. They often know the names of great thinkers, scientists and other famous people in history.

They have read classical literature. They know facts and information that many other people don't. Usually people with book-smarts are good at things like trivia games and crossword puzzles.

However, being book-smart is not everything. Sometimes people who are very educated are not so smart when it comes to life skills and people skills.

On the other hand, people who are good at dealing with practical life problems have lots of street-smarts.

People who have street-smarts may not have read as many books or earned college degrees. But they have something just as valuable -- the ability to use their experiences in many different situations. They are very aware of their surroundings.

Okay, so whether you are book-smart, street-smart or both, being smart is a good thing. Usually. It may surprise you, but getting smart is not good.

In conversation, "getting smart" does not mean gathering knowledge. It means you are being rude or impolite. It is very common to hear parents say to their children, "Do NOT get smart with me!”

And that’s not the only “smart” expression that can get you into trouble.

We often pair "smart" with "off" to make a very useful phrasal verb -- to smart off. Smarting off to someone means you are saying rude comments and showing a lack of respect.

In this context, the adjective "smart" is not good. If a child has a smart mouth, they often say disrespectful, rude things. In the classroom, students who give smart answers are trying to be funny by saying rude or inappropriate things.

Let's say there is a student who has a really smart mouth. She gives the teacher a smart answer in class one too many times. The teacher may say to her, "Do not get smart with me, young lady!" Or "Do NOT smart off in class!" Both mean, "Do not be rude!"

There is another type of "smart" that is bad.

Okay, we have all met someone who thinks they know everything about everything! Well, you can call that person a smarty-pants. These know-it-all types can be really annoying.

But please note that this insult can sound a bit childish.

So, being smart -- whether book-smart or street-smart -- is a great thing to be ... except when it’s not!