Looks a little big for a drill. Looks like it has been modified for use on one edge for sure.
I have found some mighty large gravers that were likely used for scoring large animal bones. That may be the reason for the point. Does it look like it was put there intentionally?
its definatly not just a rock ...its clearly been worked.....its definatly not a drill too wide ....i agree that its some sort of crude knife or cutting tool...or they were in the process of finishing it
For what it's worth, my first thought was hand held reamer.