1n. a road or trail that cuts off a loop or bend in an older road, thus reducing the distance to be travelled.
1859  During the past season individual enterprise has done much towards improving this trail, cut offs have been discovered which have shortened it some 20 miles.
1958  Leaving Fort Nelson, we set off for Beatton River, and were soon on the cut-off that leads from the Highway in to the airport.
2n. a channel resulting from a change in the course of a river.
1859  The ice was packed ten feet high, below Six Tree Shoot, and the Maria cut off,--where a portage of a mile had to be made, with a whale-boat, over the ice.
1900  Watch out for the open water on the Thirty Mile River, and be sure to take the big cut-off above Le Barge.
1952  Between the channels are innumerable shallow lakes and cut-offs of all sizes and shapes.