1. 推测;猜测;猜想
    If you speculate about something, you make guesses about its nature or identity, or about what might happen.

speculate的翻译

    e.g. Critics of the project speculate about how many hospitals could be built instead...
           对该项目持批评态度的人在推测如果改作他用不知可以建多少所医院。
    e.g. It would be unfair to Debby's family to speculate on the reasons for her suicide...
           猜测黛比自杀的原因对她的家人来说是不公平的。

2. 投机;做投机买卖
    If someone speculates financially, they buy property, stocks, or shares, in the hope of being able to sell them again at a higher price and make a profit.

    e.g. Big farmers are moving in, not in order to farm, but in order to speculate with rising land prices...
           大农场主正在不断涌进来，不是为了耕作，而是要利用不断上涨的地价进行投机。
    e.g. The banks made too many risky loans which now can't be repaid, and they speculated in property whose value has now dropped.
           各银行贷出去太多高风险贷款，目前无法收回，他们还进行地产投机，而地产的价值目前已经下跌了。