Prepare your own definition of learning.... should take 3 to 3.5 hours.
I suppose the length of time allocated to this activity should have alerted me to the fact I was on a rabbit warren journey - deeper and deeper, more and more forks in the burrow to note and come back to, no signposted final destination and all whilst in an extremely unfamiliar environment.
I began at Wikipedia which is a strategy some may roll their eyes at but I defend it nonetheless. Wikipedia is written in language I understand and, in the event of a term or concept being unfamiliar to me, it's likely to be underlined in blue and will deftly take me to a place where I can learn that straight away. (And then, before I know it, I will have 42 Wikipedia tabs open on my desktop and will still be clicking!)
The Wikipedia article was a very good starting point. I was pleased to immediately be able to recognize some words which aligned to Sfard's Acquisition Metaphor and a few which also brought to mind her Participation Metaphor, as well as concepts such as Identity Change.
I then went to my favourite online place - the OU Library! I literally searched 'What is Learning?' and the first hopeful hit was a book called What is Learning? by Mark Haselgrove, dated July 2016. I was very hopeful about this book as it was written in a very readable style and there were concise chapters. Hazelgrove described very well how learning is not restricted to people (animals, plants and machines all 'learn') and he made practically no mention of education or schooling at all. He began at the start of the human journey with Habituation, moving on to Conditioned Responses and there is kind of stopped. Whilst I absolutely can see how vital these early learning experiences are (we learned not to touch a fire as it hurt, we learned that if we didn't wipe our feet we got told off) I think that this is only part of what I am being asked to define.
I then found the book How We Learn by Henry Boyd Bode. My initial search made me think this was published in 2007 but the opening paragraph (where the word 'man' was used in a context where both men and women clearly should have been) made me double check and I saw it had actually been published in 1940. He made the distinction between learning a skill as an apprentice and learning 'the three Rs' as a pupil and how the method must necessarily be different. I was interested in the way he described the fact that 'learning theory' is (or was) little thought of by teachers and students who simply do what they have always done without question, and with the desired outcomes. His book went on to be far more psychological and even philosophical so I book marked it - trying to kid myself I'll come back later to learn more!
My third, and most successful hit was Education and Learning: An evidence based approach by Mellanby and Theobald from 2014. There is a nice mixture between theory and examples to demonstrate it. They look at the purpose of education, which must (surely!) be connected in some way to the purpose and nature of learning. The most interesting idea in the first few chapters is the idea of education is for the reproduction of a culture. I initially recoiled at this idea - imagining history lessons reporting colonial triumph or literature only celebrating the works of homegrown authors - but I realized that the term was intended to convey the passing on of values and, as they quoted Thomas Arnold as saying, "The best that has been known and thought."
I have also asked my considerable number of Facebook friends for ideas. Many are teachers, all have been students, but I don't know if any have studied H800! I'll report back!
My tentative first draft of the 'answer' to the posed question is: Learning is both spontaneous and deliberate and protects and maintains the learner, their community and their culture; it can be seen in the gain of knowledge and understanding; it can be for the improvement of the individual and others.