The Collaborative International Dictionary of English v.0.48:

Serpent \Ser"pent\, v. i. [imp. & p. p. Serpented; p. pr. &
   vb. n. Serpenting.]
   To wind like a serpent; to crook about; to meander. [R.] "The
   serpenting of the Thames." --Evelyn.
   [1913 Webster]