haha great question, enigma, I used to argue about this with other people in my careers studies class all the time.
Basically there are like about 5 popular theories of intelligence proposed by different people in the past century. They all suggested different perspectives on intelligence, some say it is mainly about memory and verbal fluency, some others say it has to do with biological brain capacity, and some believe it's based on the person's ability to reason. The most accepted theory in today's society is The Multiple Intelligences Theory proposed by Dr. Howard Gardner in 1983. He suggested that a person can be smart in his/her unique ways. He proposed 8 types of intelligences: spatial, lingustic, mathematic/logic, kinesthetic, musical, naturalist, intrapersonal, and interpersonal.
it's actually interesting how most of the society and school views intelligence, while they all have their different definitions of intelligence (eg. creativity, memory, learned knowledge), they would ultimately judge the person's intelligence by his/her school performance or marks. and our current education system mainly rewards and recognizes spatial and logical intelligences