While "didst an about-face" may sound like old English, it is actually a phrase that means to change one's opinion or stance abruptly. There are many synonyms that can be used to convey the same meaning. One common term is to "flip-flop," which suggests a sudden change of direction. Another similar expression is to "backpedal," which implies retreat or wavering. To "retrace one's steps" also denotes a change in direction, but with a sense of going back to something previously believed. Other synonyms for "didst an about-face" include to "reverse course," "make a U-turn," or "do an about-turn." All of these phrases convey the idea of abrupt shift in one's position or beliefs.