The Collaborative International Dictionary of English v.0.48:

Succumb \Suc*cumb"\, v. t. [imp. & p. p. Succumbed; p. pr. &
   vb. n. Succumbing.] [L. succumbere; sub under + cumbere (in
   comp.), akin to cubare to lie down. See Incumbent,
   Cubit.]
   To yield; to submit; to give up unresistingly; as, to succumb
   under calamities; to succumb to disease.
   [1913 Webster]