“I’ve got some free time” someone says. What do they mean? What is this “free time” of which they speak? What differentiates this “free time” from other times? If I have it and then fill it with something (a beer and a game of checkers with my neighbor) is it still “free” or is it now enslaved (to checkers, my neighbor, and the beer shared between us)?

In other words, can “free time” be spent doing things or does the spending of it make it somehow “un-free” time?