'Sunk fence' definitions:

Definition of 'sunk fence'

(from WordNet)
noun
A ditch with one side being a retaining wall; used to divide lands without defacing the landscape [syn: sunk fence, ha-ha, haw-haw]

Definition of 'Sunk fence'

From: GCIDE
  • Sunk \Sunk\, imp. & p. p. of Sink. [1913 Webster]
  • Sunk fence, a ditch with a retaining wall, used to divide lands without defacing a landscape; a ha-ha. [1913 Webster]