From The Collaborative International Dictionary of English v.0.48 [gcide]: Sentinel \Sen"ti*nel\, v. t. [imp. & p. p. Sentineledor Sentinelled; p. pr. & vb. n. Sentineling or Sentinelling.] 1. To watch over like a sentinel. "To sentinel enchanted land." [R.] --Sir W. Scott. [1913 Webster] 2. To furnish with a sentinel; to place under the guard of a sentinel or sentinels. [1913 Webster]