[1] : The Collaborative International Dictionary of English v.0.48

decumbent \decum"bent\, a. l. decumbens, -entis, p. pr. of
   decumbere; de- + cumbere only in comp., cubare to lie
   down.
   1. lying down; prostrate; recumbent.
      1913 webster

            the decumbent portraiture of a woman. --ashmole.
      1913 webster

   2. bot. reclining on the ground, as if too weak to stand,
      and tending to rise at the summit or apex; as, a decumbent
      stem. --gray.
      1913 webster

[2] : WordNet (r) 2.0

decumbent
     adj : lying down; in a position of comfort or rest syn: accumbent,
            recumbent, reclining
see also:
accumbent recumbent reclining 

Decumbent >> D Words
Decumbent, definition of term: Decumbent
decumbent_pag1.html