Who coined the term “machine learning”?

Question

A lot of sources attribute the definition to Arthur Samuel (1959), "the field of study that gives computers the ability to learn without being explicitly programmed", but none of these sources directly point to where he actually said the quote. Just a bunch of people saying he said that.

Some give it as his 1959 paper on checkers, but I don't find any such definition there.

Answer 1

The earliest reference appears to be:

... it is easy to see how a machine could be programmed so that it appeared to learn... whether it would in principle be possible to construct a generalized learning programme which would enable an operator, if he had sufficient patience, to 'teach' the machine any subject he chose...

• Can Machines Think?, M. V. Wilkes (1951)

C.f:

• Programming a digital computer to learn, A. G. Oettinger (1952)
• A learning machine, R. M. Friedberg (1958)

Before the term "machine-learning" itself gained currency:

• Some experiments in machine learning, H. Campaigne (Mar 1959)
• Some Studies in Machine Learning Using the Game of Checkers, A. L. Samuel (Jul 1959)
• Generalization of learning in a machine, R. J. Lee (Sep 1959)
• Two notes on machine “Learning”, H. H. Martens (Dec 1959)