There are many synonyms for the term speculating. Some of the synonyms are betting, chancing, predicting, prophesying and analyzing. Calculating, evaluating and guessing are also synonyms of the term speculating.
The term "speculative" pertains to projecting an outcome based on theory or available data. The outcome may be unknown, but is theorized by analyzing available circumstantial information or by making an educated guess. "Speculative" can also pertain to financial markets, where a prospective investor makes an investment based the idea that the investment will gain value over a period of time.
Similar to prediction.