To be franker there are too many definitions some common of them are as follows
The ability of a digital computer or computer-controlled robot to perform tasks commonly associated with intelligent beings.
A machine completing the tasks which involve a certain degree of intelligence which was previously deemed only to be done by humans.
Is the simulation of human intelligence processes by machines, especially computer systems.These processes include learning, reasoning, and self-correction.
The capability of a machine to imitate the intelligent human behavior.
Types of Artificial Intelligence (AI):
Weak AI or Narrow AI: It is focused on one narrow task, the phenomenon that machines which are not too intelligent to do their own work can be built in such a way that they seem smart. An example would be a poker game where a machine beats human where in which all rules and moves are fed into the machine. Here each and every possible scenario need to be entered beforehand manually. Each and every weak AI will contribute to the building of strong AI.
Strong AI: The machines that can actually think and perform tasks on its own just like a human being. There are no proper existing examples for this but some industry leaders are very keen on getting close to build a strong AI which has resulted in rapid progress.li>