What does the word "hobby" come from?

In the beginning, I would like to start with a definition of what is a hobby. Hobby - is something you most like to do in your free time, for example, it can be reading, drawing, knitting and so on. It is something that you like to do for brains' relaxing. It is an interesting fact that in 13th-century people used the word "hobby' for ponies. Later the word "hobby" started to describe a toy horse - hobbyhorse. After several decades people start to use first part as a description of the favourite pastime.