Here are the definitions I use, and OSHA’s
Hazard: Any facility, location, equipment, tool, job, task, or action that presents a potential of serious injury or death to any employee. This is the OSHA view. Serious injuries are those that result in time loss (beyond the three day grace period) and/or hospitalization beyond an emergency room visit.
OSHA: A hazard is the potential for harm. In practical terms, a hazard often is associated with a condition or activity that, if left uncontrolled, can result in an injury or illness.
Risk: It is related to Hazard, it is the potential of harm or loss (generally economic) and its impact to the company or individual from a potential hazard.
OSHA: The term risk is usually associated with medical conditions or exposure and is therefore centered on the health impact to employees. It does not define risk.
Incident/accident: Same thing! Some executives prefer one or the other and have specific reasons why. Another word that will be thrown at you is "event", same thing too.
OSHA: OSHA does not define accident or incident, but if you rely on “Hazard” as a base for defining any accident, incident, event or near miss, you will have a better idea of what it means.
Near Hit: The accident, incident, or event that did not happen, but would have happened except for the luck of the draw. Many believe that these occur only because of bad employee behavior. Not true, they can be the result of individual action, established process or procedure, maintenance failure, and a few others.
OSHA: OSHA does not define the term.