What is a game, and why be so Serious about it?

This blog is focused on using games for learning purposes. We often call these types of games "Serious Games" but others, and especially serious gamers, say they have been serious about their games ever since they started. So the question of what to call learning environments that have game like aspects. We could not even focus on the learning environment and instead look at what the player does with the content. In that case we are instead looking at play that has different outcomes that could be more meaningful, thus a possible name of "Meaningful Play" for our focus instead. What do you think?