When in doubt, use Webster's:
2: a rope for warping or mooring a ship or boat
Warp reffers to a large line, equivalent to an anchor rode. It can be used for warping the ship (moving by pulling against ground anchors), mooring, or can be towed as described above.
If used as a drogue it will be in a loop, one end on each stern cleat (no loop, no drag), and the loop is weighted so that it sinks, thus the term "weighted warp." It does not slow the boat much, but it can reduce yawing. The weight must be secured in such a way that if one end is let go it is not lost; the warp is retrieved by releasing one end, whic reduces the drag.
However, most boats don't carry enough rode for this to work; we don't warp into harbor anymore!