Incumbent

adj. presently holding an office or position; compulsory, necessary; resting, lying (Archaic)

n. person who currently holds an office or position

The incumbent, in politics, is the current holder of a political office. This term is usually used in reference to elections, in which races can often be defined as being between an incumbent and non-incumbent. For example, in the 2004 United States presidential election, George W. Bush was the incumbent, because he was the president in the current term while the election sought to determine the president for the following term.
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Noun
1. the official who holds an office
(synonym) officeholder
(hypernym) official, functionary
(hyponym) office-bearer
Adjective
1. lying or leaning on something else; "an incumbent geological formation"
(similar) superjacent
(classification) geology
2. currently holding an office; "the incumbent governor"
(similar) current

(n.)
A person who is in present possession of a benefice or of any office.
  

(a.)
Lying; resting; reclining; recumbent; superimposed; superincumbent.
  

(a.)
Lying, resting, or imposed, as a duty or obligation; obligatory; always with on or upon.
  

(a.)
Leaning or resting; -- said of anthers when lying on the inner side of the filament, or of cotyledons when the radicle lies against the back of one of them.
  

(a.)
Bent downwards so that the ends touch, or rest on, something else; as, the incumbent toe of a bird.
  

A current office-holder.