The Collaborative International Dictionary of English v.0.48:

Trail \Trail\ (tr[=a]l), v. t. [imp. & p. p. Trailed; p. pr. &
   vb. n. Trailing.] [OE. trailen, OF. trailler to trail a
   deer, or hunt him upon a cold scent, also, to hunt or pursue
   him with a limehound, F. trailler to trail a fishing line;
   probably from a derivative of L. trahere to draw; cf. L.
   traha a drag, sledge, tragula a kind of drag net, a small
   sledge, Sp. trailla a leash, an instrument for leveling the
   ground, D. treilen to draw with a rope, to tow, treil a rope
   for drawing a boat. See Trace, v. t.]
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   1.
      (a) To hunt by the track; to track.
      (b) to follow behind.
      (c) To pursue. --Halliwell.
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   2. To draw or drag, as along the ground.
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            And hung his head, and trailed his legs along.
                                                  --Dryden.
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            They shall not trail me through their streets
            Like a wild beast.                    --Milton.
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            Long behind he trails his pompous robe. --Pope.
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   3. (Mil.) To carry, as a firearm, with the breech near the
      ground and the upper part inclined forward, the piece
      being held by the right hand near the middle.
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   4. To tread down, as grass, by walking through it; to lay
      flat. --Longfellow.
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   5. To take advantage of the ignorance of; to impose upon.
      [Prov. Eng.]
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            I presently perceived she was (what is vernacularly
            termed) trailing Mrs. Dent; that is, playing on her
            ignorance.                            --C. Bronte.
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The Collaborative International Dictionary of English v.0.48:

Trail \Trail\, v. i.
   1. To be drawn out in length; to follow after.
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            When his brother saw the red blood trail. --Spenser.
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   2. To grow to great length, especially when slender and
      creeping upon the ground, as a plant; to run or climb.
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The Collaborative International Dictionary of English v.0.48:

Trail \Trail\, n.
   1. A track left by man or beast; a track followed by the
      hunter; a scent on the ground by the animal pursued; as, a
      deer trail.
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            They traveled in the bed of the brook, leaving no
            dangerous trail.                      --Cooper.
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            How cheerfully on the false trail they cry! --Shak.
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   2. A footpath or road track through a wilderness or wild
      region; as, an Indian trail over the plains.
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   3. Anything drawn out to a length; as, the trail of a meteor;
      a trail of smoke.
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            When lightning shoots in glittering trails along.
                                                  --Rowe.
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   4. Anything drawn behind in long undulations; a train. "A
      radiant trail of hair." --Pope.
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   5. Anything drawn along, as a vehicle. [Obs.]
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   6. A frame for trailing plants; a trellis. [Obs.]
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   7. The entrails of a fowl, especially of game, as the
      woodcock, and the like; -- applied also, sometimes, to the
      entrails of sheep.
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            The woodcock is a favorite with epicures, and served
            with its trail in, is a delicious dish. --Baird.
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   8. (Mil.) That part of the stock of a gun carriage which
      rests on the ground when the piece is unlimbered. See
      Illust. of Gun carriage, under Gun.
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   9. The act of taking advantage of the ignorance of a person;
      an imposition. [Prov. Eng.]
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   Trail boards (Shipbuilding), the carved boards on both
      sides of the cutwater near the figurehead.

   Trail net, a net that is trailed or drawn behind a boat.
      --Wright.
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WordNet (r) 3.0 (2006):

trail
    n 1: a track or mark left by something that has passed; "there
         as a trail of blood"; "a tear left its trail on her cheek"
    2: a path or track roughly blazed through wild or hilly country
    3: evidence pointing to a possible solution; "the police are
       following a promising lead"; "the trail led straight to the
       perpetrator" [syn: lead, track, trail]
    v 1: to lag or linger behind; "But in so many other areas we
         still are dragging" [syn: drag, trail, get behind,
         hang back, drop behind, drop back]
    2: go after with the intent to catch; "The policeman chased the
       mugger down the alley"; "the dog chased the rabbit" [syn:
       chase, chase after, trail, tail, tag, give chase,
       dog, go after, track]
    3: move, proceed, or walk draggingly or slowly; "John trailed
       behind his class mates"; "The Mercedes trailed behind the
       horse cart" [syn: trail, shack]
    4: hang down so as to drag along the ground; "The bride's veiled
       trailed along the ground"
    5: drag loosely along a surface; allow to sweep the ground; "The
       toddler was trailing his pants"; "She trained her long scarf
       behind her" [syn: trail, train]