1. To bet on an uncertain outcome, as of a game or sporting event. 2. To play a game for stakes, especially a game whose outcome is at largely determined by chance. 2. To take a risk in the hope of gaining an advantage or a benefit. 3. To engage in a reckless or hazardous behavior. 4. To invest in a project where little or no research has been conducted, the odds of failure are high, the intention is risk-seeking, emotions such as greed and fear are motivators, ownership of something tangible is not involved, the return is expected overnight, entertainment is the primary motivator, no economic value is added.