succumb: [15] Someone who succumbs to something is etymologically ‘lying down under’ it. The word comes via Old French succomber from Latin succumbere, a compound verb formed from the prefix sub- ‘under’ and -cumbere ‘lie’. This verbal element also produced English incumbent and recumbent, and the non-nasalized version of its stem lies behind covey, incubate, incubus, and succubus. => covey, incubate, incumbent, recumbent
succumb (v.)
late 15c., from Old French succomber "succumb, die, lose one's (legal) case," and directly from Latin succumbere "submit, surrender, yield, be overcome; sink down; lie under; cohabit with," from sub "down" (see sub-) + -cumbere "take a reclining position," related to cubare "lie down" (see cubicle). Originally transitive; sense of "sink under pressure" is first recorded c. 1600. As a euphemism for "to die," from 1849. Related: Succumbed; succumbing.