phrasal
1. : to alternately back the sails and fill the sails of a ship so as to keep it clear of the shore and obstructions while the current of a river or channel carries it down
2. : to take opposite positions alternately : alternately favor and disfavor : shilly-shally
he backed and filled and finally came to no decision at all
3. : to maneuver especially backward and forward
turn the wheel to back and fill the car around
the boar backed and filled as the dogs circulated and took nips — Newsweek