The word "within" refers to being inside or contained by something. It can describe a physical location as well as a more abstract idea, such as being inside a particular group or concept. Essentially, it implies that something is enclosed or included inside a certain boundary or limit.
The word "within" comes from Old English "wiþinnan," which is a combination of "wiþ," meaning "against" or "opposite," and "innan," meaning "inside" or "within." Over time, it evolved into its current form, retaining the core meaning of being inside or contained.