flip-flop

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

• noun The movement or sound of repeated flapping.
• noun A reversal, as of a stand or position.
• noun A backless, often foam rubber sandal held to the foot at the big toe by means of a thong.
• noun A backward somersault or handspring.
• noun An electronic circuit or mechanical device capable of assuming either of two stable states, especially a computer circuit used to store a single bit of information.
• intransitive verb To move back and forth between two conditions or circumstances, sometimes repeatedly.
• intransitive verb To reverse a stand or position.
• intransitive verb To execute a backward somersault or handspring.
• intransitive verb To move from one position to the reverse or opposite.

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

• noun A sandal, usually of rubber, secured to the foot by two straps mounted between the big toe and its neighbour.
• noun An instance of flip-flopping, of repeatedly changing one's stated opinion about a matter.
• noun computing, electronics An electronic circuit (a bistable multivibrator) that has two stable states and is thereby capable of serving as one bit of memory.
• verb To alternate back and forth between directly opposite opinions, ideas, or decisions.

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

• noun a decision to reverse an earlier decision
• verb reverse (a direction, attitude, or course of action)
• noun a backless sandal held to the foot by a thong between the big toe and the second toe
• noun a backward somersault
• noun an electronic circuit that can assume either of two stable states