I don’t see why it wouldn’t be. Pool games are shown on ESPN, if you want to buy a pool cue you go to a sporting goods store, and it takes a lot of skill to be good. Also, isn’t any game played with one or more balls considered a sport? This thread might need to be moved, I put it in GD because I argue this with my friends a lot.
It depends on which definition you prefer.
Pool is a game. Like Darts, shuffleboard and love.
Fits all of the first 3, imho.
In my opinion, yes. A sport, IMHO, is a contest of physical skill, played for its own intrinsic purpose, with criteria that determines a winner.
^ I think what most people will be divided on is whether or not the degree of “physical exertion” needed to play pool counts as physical exertion.
There are at least a half-dozen recent threads where the Teeming Masses argue over what is and isn’t a sport versus a game with no real consensus. It really matters what parameters you choose, and no two people seem to agree on those. 
right - and I was going to add something to the affect - but the defintiion does not qualify or quantify how much exertion is required.
it definitely requires more physical exertion than playing poker/chess - but less than bowling*.
*until the fights break out
IMHO, the difference between pool and poker or chess is not exertion, but that there is no genuine aspect of physical skill or exertion in poker or chess at all. A game of chess can be played by a person with no arms, or by a computer, as in fact has been done. Most of the money being won and lost in poker is being won and lost by people who never touch a real card or see their opponents. Poker and chess are fundamentally the same games whether played with physical pieces and cards or electronic representations thereof. In fact, you can play poker live, in some casinos, with electronic tables and no physical cards or chips.
Billiards, by comparison, has no analogous way of being played except with the use of cues, pool balls, and the skill to make them do what you want them to do.
Agree - except there are some pretty good pool simulation/games out there. (good to this amateurs eyes)
Debate? Sure
Great? Not so much or amazingly so, depending on one’s POV
Game Room? Certainly
Ditto football or baseball or soccer, but we don’t debate those are sports, either.
Not to me
“The main difference between the rules of a video game and the rules of a sport is that sports use the preexisting systems of the physical world in the game.” Half-Real, Jesper Juul
Every game is defined by a system of constraints. Sports are games where the real-world physical properties of objects form part of that system.
The physical properties of a pawn don’t matter.
The physical properties of a soccer ball do.
By that criterion, pool is a sport.
But what if we decide it’s a sport? 
In poker, real life play differs from online greatly in that there are many ways to bluff, read faces, intimidate, etc. that could not be done over a computer. Would you consider real life poker a sport?
Well it’s often shown on ESPN, so …
My general rule-of-thumb for “is it a sport or a game?” discussions is to find out it improved physical conditioning improves your performance. In golf, I believe it’s been shown that improving fitness improves your abilities, so that would be a sport to me. In pool, without any further evidence, I’d guess that your skill wouldn’t improve to a noticeable degree with increased physical conditioning, so that would be a game to me.
My other trick is to just accept whatever somebody else says on the matter in a discussion, so an argument is impossible. 
Well, if driving a racecar is a sport, I think billiards is too.
Actually, motor sport driving ( car and motorcycle) can be very demanding physically. To the point that drivers/riders can reach near max heart rate during a race.