The Collaborative International Dictionary of English v.0.48:

Nod \Nod\, v. t. [imp. & p. p. Nodded; p. pr. & vb. n.
   Nodding.]
   1. To incline or bend, as the head or top; to make a motion
      of assent, of salutation, or of drowsiness with; as, to
      nod the head.
      [1913 Webster]

   2. To signify by a nod; as, to nod approbation.
      [1913 Webster]

   3. To cause to bend. [Poetic]
      [1913 Webster]

            By every wind that nods the mountain pine. --Keats.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Nodding \Nod"ding\, a.
   Curved so that the apex hangs down; having the top bent
   downward.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nodding
    adj 1: having branches or flower heads that bend downward;
           "nodding daffodils"; "the pendulous branches of a weeping
           willow"; "lilacs with drooping panicles of fragrant
           flowers" [syn: cernuous, drooping, nodding,
           pendulous, weeping]

Moby Thesaurus II by Grady Ward, 1.0:

109 Moby Thesaurus words for "nodding":
   absent, absentminded, absorbed, abstracted, anesthetized, asleep,
   bagging, baggy, ballooning, bemused, castle-building, casual,
   cataleptic, comatose, daydreaming, daydreamy, distant, doped, dozy,
   dreaming, dreamy, drooping, droopy, drowsing, drowsy, drugged,
   drugged with sleep, ecstatic, elsewhere, engrossed, faraway,
   floppy, goofing off, half asleep, half-awake, heavy,
   heavy with sleep, heavy-eyed, in a reverie, in a stupor,
   in the clouds, incautious, incomplete, languid, lethargic, limp,
   loose, lop, lop-eared, loppy, lost, lost in thought, meditative,
   mooning, moonraking, museful, musing, napping, narcoleptic,
   narcose, narcotized, narcous, oblivious, off-guard, oscitant,
   out of it, pensive, pipe-dreaming, preoccupied, rapt, sagging,
   sagging in folds, saggy, sedated, sleep-drowned, sleep-drunk,
   sleep-filled, sleep-swollen, sleepful, sleeping, sleepy, slight,
   slumberous, slumbery, snoozy, somewhere else, somnolent, soporific,
   stargazing, stretchy, stuporose, stuporous, superficial, swag,
   taken up, transported, unalert, uncautious, unconscious, unguarded,
   unprepared, unready, unvigilant, unwary, unwatchful, woolgathering,
   wrapped in thought, yawning, yawny