Thesaurus article: intelligent

These are all words used to describe someone who understands and learns new things easily.

Intelligent, clever, and smart are all common ways of referring to someone who learns new things quickly and easily. Smart is more common in US English, and clever is more common in UK English.

The opposite of intelligent is unintelligent.

Someone who is intelligent and learns quickly can be called bright. Bright is often used of children.

Someone who is intelligent and quick to notice things is called sharp. Sharp is usually an approving word.

Someone who is extremely intelligent is sometimes described as brilliant.

An intelligent person who has a special ability to do a particular thing very well can be described as gifted or talented. Gifted usually implies that your ability is not one you have to work hard for but comes naturally. Talented can mean that you have worked hard to do a thing very well, or that your ability comes naturally.

The adjective intellectual can be used about someone who studies and understands complicated subjects and ideas.

The formal word cerebral can be used to describe someone who is intelligent and serious, and who enjoys serious thinking.

Wise can be used to describe someone who is intelligent as the result of experience. Wise is an approving word.

A brainy person is intelligent. This word is informal.

Someone who is knowledgeable knows a lot of things, generally or about a particular subject.

If you describe someone as astute, you mean that they understand situations well and know how to take advantage of them.