n.a ditch with one side being a retaining wall; used to divide lands without defacing the landscape
同义词：ha-hahaw-haw
英汉双解大词典
sunk fence
1.
N（名词）
a ditch, one side of which is made into a retaining wall so as to enclose an area of land while remaining hidden in the total landscape 矮墙 (Also called ha-ha)