The Collaborative International Dictionary of English v.0.48:

Recumbent \Re*cum"bent\ (-bet), a. [L. recumbens, -entis, p. pr.
   of recumbere. See Recumb, Incumbent.]
   Leaning; reclining; lying; as, the recumbent posture of the
   Romans at their meals. Hence, figuratively; Resting;
   inactive; idle. -- Re*cum"bent*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

recumbent
    adj 1: lying down; in a position of comfort or rest [syn:
           accumbent, decumbent, recumbent]

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "recumbent":
   accumbent, aslant, aslope, atilt, bevel, beveled, bias, biased,
   canting, careening, couchant, couche, crawling, crouched, debased,
   decumbent, depressed, draped, flat, groveling, horizontal,
   inclinational, inclinatory, inclined, inclining, knee-high,
   knocked flat, laid low, leaning, listing, lolling, lounging, low,
   low-built, low-hung, low-level, low-leveled, low-lying, low-set,
   low-statured, lying, lying down, neap, out of plumb, out of square,
   pitched, procumbent, prone, prostrate, raking, reclining, reposing,
   resupine, runty, shelving, shelvy, short, sideling, sidelong,
   slant, slanted, slanting, slantways, slantwise, sloped, sloping,
   sprawled, sprawling, spread, squat, squatty, stooped,
   stretched out, stumpy, supine, tilted, tilting, tipped, tipping,
   tipsy, unelevated