back and forth

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

• adverb Backward and forward; to and fro.
• adverb From side to side.

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

• adverb From one place to another and back again.
• adjective Going from one place or position to another and back again.
• noun The movement (of someone or something) forward followed by a return to the same position. May refer to a concept such as an emotional state or a relationship as well as a physical thing.
• noun idiomatic Negotiations or discussions between two or more parties, a dialog.

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

• adverb moving from one place to another and back again