intelligent

If you are intelligent, you can understand difficult ideas easily and think clearly.

Example: Any intelligent person should be able to understand this.

If an idea or something said is intelligent, it shows good understanding and clear thinking.

Example: That's probably the most intelligent comment I've heard today.

If another living thing or a machine is intelligent, it can think in ways that are similar to us.

Example: We will not likely find intelligent life of other planets.