1
- predic.
incumbent on/upon
necessary for (someone) as a duty or responsibility职责所在的, 义不容辞的： it is incumbent on all decent people to concentrate on destroying this evil.
集中力量消灭这类邪恶是所有正派人义不容辞的责任。
2
- attrib.(of an official or regime) currently holding office（官员）在职的, 在任的; （政权）当权的：
the incumbent President had been defeated.
在任总统被击败了。
2.1
- denoting a company having a sizeable share of a market（公司）占市场份额大的：
powerful incumbent airlines.
占市场份额相当大的航空公司。
- the holder of an office or post现任者, 在任者。
词源
late Middle English (as a noun)： from Anglo-Latin incumbens, incumbent-, from Latin incumbere 'lie or lean on'， from in- 'upon' + a verb related to cubare 'lie'.