—adj.
1 (foll. by on, upon) resting as a duty (it is incumbent on you to warn them).
2 (often foll. by on) lying, pressing.
—n. the holder of an office or post, esp. an ecclesiastical benefice.
Etymology: ME f. AL incumbens pres. part. of L incumbere lie upon (as IN-(2), cubare lie)
Useful english dictionary. 2012.