There are probably as many definitions of intelligence as there are experts who study it. Some are following:
A very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly (conceptually), comprehend complex ideas, learn quickly and learn from experience.
(Gottfredson, L.S, 1997).
Capacity for learning, reasoning, understanding, and similar forms of mental activity, aptitude (ability) in grasping truths, relationships, facts, meanings, etc.
The faculty of understanding.
Knowledge of an event, circumstance, etc, received or imparted news or information.
The gathering or distribution of information, especially secret information.
Intelligence is the ability of: abstract thought understanding communication reasoning learning planning Problem solving
What is Artificial Intelligence (AI)?
“Artificial Intelligence (AI) is the intelligence exhibited by machines or software, and the branch of computer science that develops machines and software with intelligence”.
“Artificial intelligence (AI) is the intelligence of machines and the branch of computer science which aims to create it”.
Major AI researchers and textbooks define the field as "the study and design of intelligent agents” where an intelligent agent is a system that perceives its environment and takes actions that maximize its chances of success.
John McCarthy, who coined the term in 1955, defines it as "the science and engineering of making intelligent machines."
AI is the part of computer science concerned with designing intelligent computer systems, that is, computer systems that exhibit the characteristics we associate with intelligence in human behavior.
Understanding languages, learning, reasoning,
Solving problems, and so on.
(Barr and Feigenbaum, 1981)