You can think about the context as a wrapper for related "things" such as HttpContext, DbContext, ObjectContext. i.e.: HttpContext contains any information you can reach for HTTP related operations.
DbContext contains the methods and properties for database communication. Likewise ObjectContext.
I would say it's a placeholder or container of related things for something.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…