Wordnet 3.0
ADVERB (1)
1. 
 moving from one place to another and back again; 
- Example: "he traveled back and forth between Los Angeles and New York"- Example: "the treetops whipped to and fro in a frightening manner"- Example: "the old man just sat on the porch and rocked back and forth all day"[syn: back and forth, backward and forward, to and fro]
WordNet (r) 3.0 (2006):
backward and forward
    adv 1: moving from one place to another and back again; "he
           traveled back and forth between Los Angeles and New
           York"; "the treetops whipped to and fro in a frightening
           manner"; "the old man just sat on the porch and rocked
           back and forth all day" [syn: back and forth, backward
           and forward, to and fro]