A ditch is a long trench or pit dug into the ground. If your lawns are always soggy, build a drainage ditch for the excess water to flow into.
A ditch can be a man-made trench, usually long and narrow, dug into the earth, or a natural ditch made by flowing water. Originally used for farming, we now use ditch for any pit in the ground. Ditch can also be a verb meaning to toss something or forsake it. You can ditch a plan that's going wrong, or a boyfriend who is misbehaving. If you make an emergency crash landing, you ditch your plane.