The Concise Oxford Dictionary, 1975 edition: entertainment: amusement, public performance or show
IMO Charles is entertaining us every time he steps outside the door and even behind close doors; one of his very private telephone conversations entertained us immensely. His very existence entertains us.
He entertains the passers by who stop to watch him as he's walking to his car or into a building to open something or other or to present medals to servicemen, and he entertains the people who attend the functions, and he entertains the rest of us who read about what he's done and look at the photos and video clips.
Just looking at his clothing and wondering who put the combinations together diverts from our mundane existences and entertains us, and we are especially entertained when we see him in his Highland Games outfits, stalking and shooting outfits, unusual and sometimes outlandish outfits he dons during overseas trips and his fancier getups such as his various uniforms for different events. We wonder about his medals and his ribbons and decorations and things that are alien to most of us. And we like to see what his wife is wearing when she accompanies him to these events, especially the formal events where they are in evening wear and wearing bling and decorations. His facial expressions entertain us: we comment on whether he is smiling, or laughing, or looking bored or sad.
I waited an hour in the January sun on Australia Day, 1998, to watch a car carrying him and Diana drive around the corner I was standing on. I was entertained by watching the police close the roads, and by seeing the official vehicles approach and watching other people stop to watch. And I was entertainined by the glimpse I got of Charles & Diana inside the car, then by watching the streets return to normal. That unexpected event was the highlight of what would otherwise have been a fairly uneventful day for me.
Even when Charles is doing something worthy like writing letters about the environment, or initiating some Prince's Trust project, etc., he is entertaining us because many of us read about those things solely because of who he is, and only because of who he is and the institution of which he is a part, and we discuss whether he is being too political for the PoW.
In a way the RF is like a living collection of a particular species of animal or plant. Wherever he goes and whatever he's doing, Charles is an entertainment on some level, and so are all the other members of the RF.