a hypothesis that has been formed by speculating or conjecturing (usually with little hard evidence); "speculations about the outcome of the election"; "he dismissed it as mere conjecture"
an investment that is very risky but could yield great profits; "he knew the stock was a speculation when he bought it"
an elastic material obtained from the latex sap of trees (especially trees of the genera Hevea and Ficus) that can be vulcanized and finished into a variety of products
any of various synthetic elastic materials whose properties resemble natural rubber
returned for lack of funds; "a rubber check"; "a no-good check"