The term "guess-so" is often used in casual conversation to convey uncertainty or a lack of confidence in one's answer or response. There are several synonyms that can be used to express the same sentiment, including "perhaps," "maybe," "possibly," "probable," "doubtful," "uncertain," "tentative," "equivocal," and "ambivalent." Each of these words carries a slightly different connotation, but they all indicate a degree of uncertainty or hesitation. It's important to choose the appropriate synonym based on the context of the conversation and the level of conviction one wishes to express.