Able means having the power, skill, or means to do something. When you're able to ride a bike, you have the physical coordination and balance to do it. When a scientist is able to solve a complex problem, she has the knowledge and intelligence required.

The word often appears in phrases like “able to” followed by a verb: able to swim, able to read, able to help. It describes capability or capacity. A student might not be able to lift a heavy box alone but becomes able when a friend helps. A young child isn't able to drive a car, but will be able to after years of growing up and learning.

Able also describes someone with talent or competence. An able student learns quickly and performs well. An able leader makes good decisions and guides others effectively. When used this way, it's a compliment suggesting real skill and reliability.

The opposite is unable, meaning lacking the power or means to do something. You might be unable to attend a party because you're sick, or unable to answer a question because you haven't learned that material yet. Being unable to do something isn't shameful; it simply means you currently lack what's needed, whether that's time, knowledge, permission, or support.