Meaning of word agile

Scrum:

Scrum is an agile software development model based on multiple small teams working in
an intensive and interdependent manner. The term is named for the scrum (or scrummage)
formation in rugby, which is used to restart the game after an event that causes play to
stop, such as an infringement. 
Scrum employs real-time decision-making processes based on actual events and
information. This requires well-trained and specialized teams capable of selfmanagement, communication and decision-making. The teams in the organization work
together while constantly focusing on their common interests.

XP:

Extreme Programming is a discipline of software development based on values of
simplicity, communication, feedback, and courage. It works by bringing the whole team
together in the presence of simple practices, with enough feedback to enable the team to
see where they are and to tune the practices to their unique situation.
In Extreme Programming, every contributor to the project is an integral part of the “Whole
Team“. The team forms around a business representative called “the Customer”, who sits
with the team and works with them daily.
Extreme Programming teams use a simple form of planning and tracking to decide what
should be done next and to predict when the project will be done. Focused on business
value, the team produces the software in a series of small fully-integrated releases that
pass all the tests the Customer has define.

Agility Summary:

• “The ability to create and respond to change in order to profit in a turbulent global
business environment
• The ability to quickly reprioritize use of resources when requirements, technology,
and knowledge shift
• A very fast response to sudden market changes and emerging threats by intensive
customer interaction
• Use of evolutionary, incremental, and iterative delivery to converge on an optimal
customer solution
• Maximizing the business value with right-sized, just enough, and just-in-time
processes and documentation

Reference: "Making Sense of Agile Project Management: Balancing Control and Agility" by Charles Cobb. 2011