The word conjecture is commonly used when describing an opinion or idea that is based on incomplete information or without sufficient evidence to support it. There are many different synonyms that can be used instead of conjecture, depending on the context and tone of the sentence. Some possible synonyms include speculation, hypothesis, theory, assumption, inference, supposition, proposition, and postulation. While all of these words share a similar meaning to conjecture, each has its own subtle nuances that can be used to convey different shades of meaning. For example, a scientist might use the word hypothesis when describing an untested theory, while a journalist might use the word speculation when describing rumors or gossip. Ultimately, the choice of synonym will depend on the speaker's intentions and rhetorical goals.