Barack Obama is the incumbent president.
The incumbent is the current office holder, the "challanger' is the person running against the incumbent
An incumbent is an elected official who holds an office and is running for reelection.
Diem until '63. Thieu until the end.
A governor already in office.
The mayor who is in office and running for reelection.
the prisident
vp
George Bush
Prisident
The possessive form for the singular noun incumbent is incumbent's.
John Wilkes Booth.
Right now it is our prisident mr.Rajapaksha... He brought peace to srilanka after 30 years... We respect u MR PRISIDENT..........
The incumbent is the current office holder, the "challanger' is the person running against the incumbent
The incumbent is the current holder of a political office. To vote "non-incumbent" would mean to vote for the challenger to the incumbent's position.
Woodrow Wilson.
Senate
Abraham Lincoln