boomerang

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A flat, curved, usually wooden missile configured so that when hurled it returns to the thrower.
• noun A statement or course of action that backfires.
• intransitive verb To have the opposite effect from the one intended; backfire.

from The Century Dictionary.

• noun A missile weapon of war and the chase, used by the aborigines of Australia, consisting of a rather flat piece of hard wood bent or curved in its own plane, and from 16 inches to 2 feet long.
• noun Hence Figuratively, any plan, measure, or project the consequences of which recoil upon the projector, and are therefore the opposite of those intended or expected.

from the GNU version of the Collaborative International Dictionary of English.

• noun A very singular missile weapon used by the natives of Australia and in some parts of India. It is usually a curved stick of hard wood, from twenty to thirty inches in length, from two to three inches wide, and half or three quarters of an inch thick. When thrown from the hand with a quick rotary motion, it describes very remarkable curves, according to the shape of the instrument and the manner of throwing it, often moving nearly horizontally a long distance, then curving upward to a considerable height, and finally taking a retrograde direction, so as to fall near the place from which it was thrown, or even far in the rear of it.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A flat curved airfoil, that spins about an axis perpendicular to the direction of flight, that was originally used in various parts of the world as hunting weapons or, in returnable types, for sports or training.
• verb To return to the starting point.
• verb To travel in a curved path.
• verb To return or rebound unexpectedly, especially when the result is undesired; to backfire.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb return to the initial position from where it came; like a boomerang
• noun a miscalculation that recoils on its maker
• noun a curved piece of wood; when properly thrown will return to thrower