Reverse one's opinion or course of action completely. Also 'do a flip-flop' or 'do a one-eighty.'
Examples:
- The board did an about-face on acquiring more land.
- We expected Dad to do a flip-flop concerning our vacation plans.
Origin: First term from first half of 1900s; variants from second half of 1900s.
Synonyms: do a flip-flop, do a one-eighty