Source : Webster's Revised Unabridged Dictionary (1913)

Sentinel \Sen"ti*nel\, v. t. [imp. & p. p. {Sentineled}or
   {Sentinelled}; p. pr. & vb. n. {Sentineling} or
   {Sentinelling}.]
   1. To watch over like a sentinel. ``To sentinel enchanted
      land.'' [R.] --Sir W. Scott.

   2. To furnish with a sentinel; to place under the guard of a
      sentinel or sentinels.