Source : Webster's Revised Unabridged Dictionary (1913)

Incumbent \In*cum"bent\, a. [L. incumbens, -entis, p. pr. of
   incumbere to lie down upon, press upon; pref. in- in, on +
   cumbere (in comp.); akin to cubare to lie down. See
   {Incubate}.]
   1. Lying; resting; reclining; recumbent; superimposed;
      superincumbent.

            Two incumbent figures, gracefully leaning upon it.
                                                  --Sir H.
                                                  Wotton.

            To move the incumbent load they try.  --Addison.

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

            All men, truly zealous, will perform those good
            works that are incumbent on all Christians. --Sprat.

   3. (Bot.) 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. --Gray.

   4. (Zo["o]l.) Bent downwards so that the ends touch, or rest
      on, something else; as, the incumbent toe of a bird.

Incumbent \In*cum"bent\, n.
   A person who is in present possession of a benefice or of any
   office.

         The incumbent lieth at the mercy of his patron.
                                                  --Swift.

Source : WordNet®

incumbent
     adj 1: lying or leaning on something else; "an incumbent geological
            formation"
     2: currently holding an office; "the incumbent governor"
     n : the official who holds an office [syn: {officeholder}]