[in-kuhm-buh
nt] 
| 1. | holding an indicated position, role, office, etc., currently: the incumbent officers of the club. |
| 2. | obligatory (often fol. by on or upon): a duty incumbent upon me. |
| 3. | Archaic. resting, lying, leaning, or pressing on something: incumbent upon the cool grass. |
| 4. | the holder of an office: The incumbent was challenged by a fusion candidate. |
| 5. | British. a person who holds an ecclesiastical benefice. |
One who holds a public office. By virtue of their experience in office, their exposure to the public, and their ability to raise campaign funds, incumbents usually have a significant advantage over opponents if they choose to run for reelection.
incumbent on
Also, incumbent upon. Imposed as an obligation or duty on, obligatory for. For example, He felt it was incumbent on us all to help the homeless. [Mid-1500s]