An incumbent is the current holder of an office, position, or role.
The term is used as both
Depending on the context, the word can mean:
During an election, the incumbent is the politician who currently holds the seat, regardless of whether they are running for re-election.
It refers to a company or individual currently holding a specific position, contract, or a dominant market share in an industry.
When followed by on or upon, the word means morally binding, necessary, or required as a duty.
You can learn more about its historical origins and usage at Merriam-Webster or explore business contexts on Investopedia.