An astern direction is behind or towards the back of something.
When we talk about sailing, 'astern' can be used to give directions. For example, if you're on a boat and someone tells you to move astern, it means they want you to head in the opposite direction from where you were going. This way, you'll go backwards, away from your original course. But even in everyday life, 'astern' can be helpful when we talk about directions or positions. It's not a word that people use every day, but it can come up if someone is talking about navigation, like pilots or sailors, or just explaining where something is located on a map or diagram.
Behind (a vessel); in the rear.
