2.AdjectiveGoing from one place or position to another and back again.
"The back and forth movement of the tide causes erosion of the coastline."
3.NounThe 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.
4.NounNegotiations or discussions (not necessarily fruitful) between two or more parties; a dialog.