This word was adopted into English in the 14th century, and has been used to describe things that are nimble, quick, and adaptable ever since.
While the term has been around for a long time, it gained particular significance in the software development world in the late 1990s and early 2000s with the emergence of the Agile Manifesto.
This manifesto outlined a new approach to software development that emphasized flexibility, collaboration, and rapid iteration over rigid planning and lengthy development cycles. This approach is known as Agile software development, and the term "agile" has become closely associated with it.