名詞 incumbent:

1. the official who holds an office
   同義詞：officeholder

形容詞 incumbent:

1. lying or leaning on something else
2. necessary (for someone) as a duty or responsibility; morally binding
3. currently holding an office

1. It is incumbent upon justice to give some warnings of their doubt about a case.
   法官有責(zé)任提醒人們有關(guān)他們對(duì)案件的疑問(wèn)。
2. It's incumbent on you to advise your son before he leaves home.
   在你兒子離家前給他忠告是你義不容辭的事。
3. The quality or condition of being incumbent.
   有義務(wù)負(fù)有義務(wù)的性質(zhì)或狀況

in.cum.bent

adj.（形容詞）
Imposed as an obligation or a duty; obligatory:
有義務(wù)的：強(qiáng)加責(zé)任或任務(wù)的；有義務(wù)的：
例句：
felt it was incumbent on us all to help.
感到我們大家都來(lái)幫助是義不容辭的

Lying, leaning, or resting on something else:
憑依的，依靠的：躺、靠或放在其它物上的：
例句：
incumbent rock strata.
依附的巖石層

Currently holding a specified office:
在職的：當(dāng)前任某一特定職位的：
例句：
the incumbent mayor.
在職的市長(zhǎng)

n.（名詞）
A person who holds an office or ecclesiastical benefice:
任職者：行政部門或教會(huì)中的任職者：
例句：
defeated the incumbent in a close election.
在一場(chǎng)勢(shì)均力敵的選舉中擊敗在職者

來(lái)源：
Middle English [holder of an office]
中古英語(yǔ) [在職者]
from Medieval Latin incumbôns incumbent-
源自 中世紀(jì)拉丁語(yǔ) incumbôns incumbent-
from Latin [present participle of] incumbere [to lean upon, apply oneself to]
源自 拉丁語(yǔ) [] incumbere的現(xiàn)在分詞 [靠在…上，致力于]
in- [on] * see in- 2
in- [在…上] *參見 in-2
-cumbere [to recline]
-cumbere [斜倚，向后靠]

【引伸】
incum.bently
adv.（副詞）