Id Est, also known as i.e., is a Latin expression that is commonly used in English writing to signify "that is" or "in other words". However, there are many other synonyms that you can use instead of id est to convey a similar meaning. Some of the alternatives include, "namely", "to wit", "specifically", "meaning", "that is to say", "in essence", "in simple terms", "in other words", and "to clarify". These synonyms can be used interchangeably to explain and clarify complex or unfamiliar concepts in your writing, whether you are writing an academic paper or just communicating in everyday conversations.