FIRST robotics competitions are, without question, a sport. Look up the definition of sport in any dictionary and it will read something like this:
"A sport consists of a physical and mentally competitive activity carried out with a recreational purpose for competition, for self-enjoyment, to attain excellence, for the development of a skill, or some combination of these. A sport has physical activity, side by side competition, self-motivation and a scoring system. The difference of purpose is what characterises sport, combined with the notion of individual (or team) skill or prowess."
Source:
http://en.wikipedia.org/wiki/Sport (click and read on for more info on what a sport is and the history of sports if you are so inclined)
After all, if fishing is a sport then FIRST competitions are most definitely a sport. However, FIRST as a whole is much more than a sport because the competitions are only part of FIRST. The real question is how do you define a World changing, one of a kind, life altering experience like FIRST with only one word?