| Term | Definition |
| total certainty | All the necessary information is available for making the right decision |
| uncertainty | decisions are taken without having all the information |
| total uncertainty | extreme case of complete absence of information |
| opportunity | The cumulative effect of the chances of uncertain occurrences which will affect project objectives positively. Opportunity is the opposite of risk. |
| Project Risk | is the cumulative effect of the chances of uncertain occurrences adversely affecting project objectives |
| net project risk | the cumulative net effect of the chances of both adverse and favorable consequences affecting project objectives. |