The Dawes Act drafters didn't use the word "allotment" because they were trying to win at Word Bingo. There's a reason they didn't just say "land."

In the opening line, it is stated that the intention was to make a law that would […] provide for the allotment of lands in severalty to Indians on the various reservations. Now, this is no "Forty Acres and a Mule" /reconstruction/society.html. There were going to be rules and stipulations to follow if those folks wanted their land. Plus, it wasn't really going to be their land, remember? It was going to be held in trust by the government for twenty-five years, to make sure the allotments were being used in severalty (i.e., separately, not communally) and utilizing European farming methods.

This is pretty key to the Dawes Act. We weren't giving away land, more like redistributing it under the watchful eye of the U.S. government. We were taking it away from the tribe, and then giving them different land to use under close supervision. Once again, Dawes and his supporters found a way to make theft sound almost philanthropic.