Diachronically is an adverb that refers to something that occurs over a period of time or changes through time. Some synonyms that can be used instead of diachronically include historically, chronologically, progressively, sequentially, and temporally. All these terms refer to events, changes, or processes that take place over time, either moving forward or backward. They can be used in various contexts, such as history, linguistics, anthropology, or sociology to describe how things evolve or progress in time. Whether discussing the evolution of a language, the development of a culture, or the advancement of technology, these synonyms can help to convey the idea that something has changed or developed over time.