Definition of Sports

Spencer brings up a good point...how do we define a sport? Something including a ball doesn't cut it since hockey and swimming are out. Something athletic doesn't work, cause curling is an "olympic sport" (C'mon on! How much effort could that take!!!) Is it something with competition? Then that would include things like poker and competitive hot dog eatting, both of which are hardly sports, yet they're on ESPN??? Basically what is a sport?