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

picket \pick"et\, n. f. piquet, properly dim. of pique spear,
   pike. see pike, and cf. piquet.
   1. a stake sharpened or pointed, especially one used in
      fortification and encampments, to mark bounds and angles;
      or one used for tethering horses.
      1913 webster

   2. a pointed pale, used in marking fences.
      1913 webster

   3. probably so called from the picketing of the horses.
      mil. a detached body of troops serving to guard an army
      from surprise, and to oppose reconnoitering parties of the
      enemy; -- called also outlying picket.
      1913 webster

   4. by extension, men appointed by a trades union, or other
      labor organization, to intercept outsiders, and prevent
      them from working for employers with whom the organization
      is at variance. cant
      1913 webster

   5. a military punishment, formerly resorted to, in which the
      offender was forced to stand with one foot on a pointed
      stake.
      1913 webster

   6. a game at cards. see piquet.
      1913 webster

   inlying picket mil., a detachment of troops held in camp
      or quarters, detailed to march if called upon.

   picket fence, a fence made of pickets. see def. 2, above.
      

   picket guard mil., a guard of horse and foot, always in
      readiness in case of alarm.

   picket line. mil.
      a a position held and guarded by small bodies of men
          placed at intervals.
      b a rope to which horses are secured when groomed.

   picketpin, an iron pin for picketing horses.
      1913 webster
see also:
pike piquet outlying picket inlying picket picket fence picket guard 
picket line picketpin 

[2] : WordNet (r) 2.0

picket fence
     n : a fence made of upright pickets syn: paling
see also:
paling 

Picket Fence >> P Words
Picket Fence, definition of term: Picket Fence
picket+fence_pag1.html

Fence >> F Words
Fence, definition of term: Fence
fence_pag1.html

Picket >> P Words
Picket, definition of term: Picket
picket_pag1.html

Fence In >> F Words
Fence In, definition of term: Fence In
fence+in_pag1.html

Picket Line >> P Words
Picket Line, definition of term: Picket Line
picket+line_pag1.html

Ring Fence >> R Words
Ring Fence, definition of term: Ring Fence
ring+fence_pag1.html