When it comes to making assumptions or presumptions without any factual evidence, "wild guesses" is the term we often use. However, there are several other synonyms to express the same meaning such as conjectures, speculations, suppositions, estimations, hunches, assumptions, surmises, theories, and predictions.
By using these synonyms, we can make our conversations more interesting and diverse. For instance, instead of saying "I am making a wild guess," we can say, "My estimation is that the project will be delayed." Similarly, instead of making a baseless assumption, we can say, "I have a hunch that she will resign from the company." Thus, using synonyms can help to communicate our ideas more effectively and add variety to our vocabulary.