You'll notice each of these definitions have words and phrases in common - 'planning' features front and centre in Kristina's and Margot's definitions, and Michael's is in a similar vein, talking about 'defining the process'.
All of these definitions are heavily-weighted towards planning and process - in each they take centre stage. This makes me a little uncomfortable.
I'm in no way suggesting that these definitions are incorrect. Planning and processes are of course imperative. But planning and processes concern delivery. Planning, developing, and managing are things you do after you’ve determined your strategy.To my mind the issue with these definitions is that the strategy which underpins the content you'll create is secondary to the planning and processes.