Definition.com
Machine learning is the enactment of that old million-monkeys-writing-Shakespeare joke.
Definition.com
Machine learning is enabling computers to do research, which is another way of saying, enabling them to do science.
Definition.com
Machine learning is instigating a computer to compile data in a way that it becomes an algorithm
Definition.com
Machine learning is much like kindergarden. It consists in sorting, pattern making, classifying, and clustering similar thing things.