When adopting agile software development techniques across a large number of teams within your organization it is important to provide a definition for what agile software development is, in addition to criteria for what it means to be agile. Many people will point to the four values of the Agile Manifesto and claim that's a good definition. Well... it might be a good definition for the visionaries and early adopters among us, but for people on the right-hand side of the technology adoption chasm (the early majority, late majority and the laggards) this isn't enough. Don't get me wrong, I'm a firm believer in the agile values but I like to cast them as philosophies instead of as a definition.

At IBM Software Group, the definition of disciplined agile software delivery which we have been sharing with our customers is:Disciplined agile software delivery is an evolutionary (iterative and incremental) approach to delivery which regularly produces high quality software in a cost effective and timely manner. It is performed in a highly collaborative and self-organizing manner within an appropriate governance framework, with active stakeholder participation to ensure that the team understands and addresses the changing needs of its stakeholders. Disciplined agile delivery teams provide repeatable results by adopting just the right amount of ceremony for their situation.

I think that this is a pretty good definition, although I have no doubt that we'll evolve it over time.

I also suspect that the agile community will never settle on a common definition for what agile is and more than likely are smart enough not to even try. ;-)
Further reading:

• Agile Criteria
• Agile Manifesto
• Rational's Agile Software Development Home Page (for webcasts, whitepapers, ...)
• Disciplined Agile Delivery website