v.1. To be located to the rear of something: The stables are behind the barn. I couldn't see the whole stage because my seat was behind a pillar.
2. To be late or slow in something: We are all behind in our work. She was ahead of the other bicyclists for a while, but now she's behind. He spends too much money and is always behind on his bills.
3. To perform less well or advance more slowly than others: Your child is behind in math skills and will need extra lessons.
4. To offer support or assistance to somebody or something, especially when one does not directly take part in the activities supported or is unknown: Don't worry; I'm behind you completely in your endeavors. Who was really behind the assassination attempt?