In trice is a phrase that means in a very short amount of time. There are several synonyms that are most suitable to use interchangeably with this phrase. One of these words is "quickly," which means to do something with speed or urgency. Another synonym is "instantly," which implies that something happens immediately, without delay. Additionally, the words "swiftly" and "rapidly" both convey the meaning of speedy movement or action. "Suddenly" can also be used as a synonym for in trice since both carry the element of unexpectedness in their meaning. These words are all useful options to have in your vocabulary when you want to convey that something happens fast.