(~es)
1.
A ~ is a long narrow channel that is cut into the ground, for example in order to lay pipes or get rid of water.
N-COUNT
2.
A ~ is a long narrow channel in the ground used by soldiers in order to protect themselves from the enemy. People often refer to the battle grounds of the First World War in Northern France and Belgium as the ~es.
We fought with them in the ~es.
...~ warfare.
N-COUNT: usu the N in pl, N n