"Da's" is a colloquial term that is typically used as a contraction for "that is". If you're looking for synonyms to replace "da's", there are a few options you can use to make your writing more varied and interesting. Some synonyms for "that is" include "i.e.", "namely", "to be specific", "in other words", and "in essence". These alternatives can help you to vary your language and make your writing sound more sophisticated and nuanced. Whether you're composing an academic essay or a casual blog post, using a variety of synonyms can enhance your style and make your writing more engaging for your audience.