The phrase "didst an about face" is an archaic expression that means to turn or reverse direction abruptly. Some synonyms for this phrase include "turned on a dime," "made a U-turn," "pivoted," "reversed course," and "switched gears." These expressions can be used in a variety of contexts, such as describing a change in a person's attitude or behavior, a sudden change in a situation, or a shift in a political or business strategy. While "didst an about face" may have fallen out of common usage, these synonyms provide modern alternatives that can more effectively convey the intended meaning.