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"
a commercial product that refills a container with its appropriate contents; "he got a refill for his ball-point pen"; "he got a refill for his notebook"
a prescription drug that is provided again; "he got a refill of his prescription"; "the prescription specified only one refill"