How would you define 'trenches'?

Question

I need a definition of trenches. Like in WWi.. to answer the question

what are trenches?

Answer 1

 A trench is defined as  a type of excavation or depression in the ground. Trenches are commonly known for being  deeper than they are wide (as opposed to a wider gully or ditch), and by being narrow compared to their length (as opposed to a simple hole). Simply it can be defined as a deep forough or a ditch.