fosse = a ditch or moat

Avebury had at one time within a great rampart and a fosse, which is still forty feet deep, a large circle of rough unhewn stones, and within this two circles each containing a smaller concentric circle.

swale = a low tract of land, especially when moist or marshy; shallow troughlike depression that carries water mainly during rainstorms or snow melts

I went to the top of a hill and saw the colt at the far side of the pasture in what we call the swale -- low, wet ground, where weeds abound.

sward = land covered with grassy turf; a lawn or meadow

The moonlight on the lawn was tremulous, as if the sward were a rippling sea.

wold = an unforested rolling plain; a moor; a grassland

The house stood out in the open, a broad wold, devoid of trees, the sparse vegetation stubbled with smooth rocks.