to consider by turning a subject in the mind, and viewing it in its different aspects and relations; to meditate; to contemplate; to theorize; as, to speculate on questions in religion; to speculate on political events.-to view subjects from certain premises given or assumed, and infer conclusions respecting them a priori.-to purchase with the expectation of a contingent advance in value, and a consequent sale at a profit; -- often, in a somewhat depreciative sense, of unsound or hazardous transactions; as, to speculate in coffee, in sugar, or in bank stock.-to consider attentively; as, to speculate the nature of a thing.