| an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle. |
| a gadget; dingus; thingumbob. |
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]