The Free Online Dictionary says:

flip-flop
(flĭp′flŏp′)
n.
1. The movement or sound of repeated flapping.
2. A reversal, as of a stand or position: a foreign policy flip-flop.
3. A backless, often foam rubber sandal held to the foot at the big toe by means of a thong.
4. A backward somersault or handspring.
5. 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.
v. flip-flopped, flip-flop·ping, flip-flops
v.intr.
1. To move back and forth between two conditions or circumstances, sometimes repeatedly: "The weather has flip-flopped between sweltering heat and violent storms" (New York Times).
2. To reverse a stand or position: "With the board having flip-flopped over zoning issues in the last several years, residents are looking to this fall's election for clarity" (Eugene L. Meyer).
3. To execute a backward somersault or handspring.
v.tr.
To move from one position to the reverse or opposite: The coach flip-flopped the linemen.
flip′-flop′per n.