Synonyms for Incumbent:

adj.

obligatory (adjective)
compelling, urgent, binding, necessary.

n.

career woman, ancillary, apparatchik, designated hitter, duty officer, cowboy, breadwinner, auxiliary, desk person, commuter. in someone's employ, in the line of duty, service, hold-down, working, employment, in harness, full employment, be back in business. incumbent (noun)
current, officeholder, superjacent.
inhabitant (noun)
denizen, citizen, inmate, inhabitant, dweller, tenant, lodger, occupant, population, populace, aboriginal, native, resident.
officeholder (noun)
occupant.
person (noun)
officeholder.

Other synonyms:

full employment. employment. working. service. Other relevant words:
urgent, working, current, necessary, employment, binding, officeholder, compelling, superjacent.

Usage examples for incumbent

  1. As a lengthy silence had elapsed, Michael felt that it was incumbent on him to be getting on his way. – There was a King in Egypt by Norma Lorimer
  2. But grant that the sort of recognition we gave of the right of the citizen to be guaranteed a subsistence was a mockery more brutal than its total denial would have been, and that a far larger interpretation of its duty in this respect was incumbent on the state, yet how does it logically follow that society is bound to guarantee or the citizen to demand an absolute economic equality? – Equality by Edward Bellamy
  3. Presently the barrage began, and now both saw that it was incumbent on them to remain up there as long as possible to assist the new Allied assault by rendering their barrage effective. – Our Pilots in the Air by Captain William B. Perry