The Collaborative International Dictionary of English v.0.48:

Spoor \Spoor\ (sp[=oo]r), n. [D. spoor; akin to AS. spor, G.
   spur, and from the root of E. spur. [root]171. See Spur.]
   The track or trail of any wild animal; as, the spoor of an
   elephant; -- used originally by travelers in South Africa.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spoor \Spoor\, v. i.
   To follow a spoor or trail. [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

spoor
    n 1: the trail left by a person or an animal; what the hunter
         follows in pursuing game; "the hounds followed the fox's
         spoor"

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "spoor":
   aroma, breath, broad hint, catchword, clue, condensation trail,
   contrail, course, cue, cue word, definite odor, detectable odor,
   effluvium, emanation, essence, evidence, exhalation, flavor,
   footstep, fragrance, fume, gentle hint, gesture, glimmer,
   glimmering, hint, hot lead, implication, index, indication,
   inkling, innuendo, insinuation, intimation, key, key word, kick,
   lead, line, look, nod, nudge, odor, path, piste, prompt, redolence,
   savor, scent, sign, signal, signs, smell, stench, step,
   subtle odor, suggestion, suspicion, symptom, telltale, tip-off,
   trace, traces, track, tract, trail, vapor trail, vestige, wake,
   whiff, whisper, wink