The phrase "at standstill" can have several antonyms, depending on the context. If it refers to a situation where progress or movement has stopped or stalled, the antonyms could be "in motion," "dynamic," or "progressive." On the other hand, if "at standstill" means a state of tranquility or stillness, antonyms could include "chaotic," "restless," or "turbulent." It is important to consider the context in which the phrase is used to identify appropriate antonyms. For example, in a traffic situation, the antonym for "at standstill" could be "flowing," "moving," or "fleeting." In conclusion, antonyms for the phrase "at standstill" vary depending on the context and interpretation of the phrase.