a barrier, e.g. of wire or boards, intended to prevent escape or intrusion or to mark a boundary
Good fences make good neighbors — Robert Frost
an upright obstacle to be jumped by a horse, e.g. in showjumping or steeplechasing
a protective guard on a tool or piece of machinery
informal a receiver of stolen goods
mend one's fences
to make peace after a quarrel
[with allusion to the need to keep boundary fences in good repair to remain on friendly terms with one's neighbours]sit on the fence
to adopt a position of neutrality or indecision
fenceless adj
[Middle English fens, short for defens defence]