UX Glossary · A
Agile UX
Also: Lean UX
Practising user-centred design inside Agile delivery, usually by running research and design slightly ahead of build.
Agile UX is the set of adaptations that let design and research work inside Agile delivery rather than in front of it. The core problem it solves is timing: developers need decisions now, and useful research takes longer than a sprint.
The dual-track pattern
The most widely used answer is dual-track, described by Marty Cagan as parallel discovery and delivery. Discovery runs continuously, validating what should be built; delivery builds what discovery has already validated. Design for a given feature is done a sprint or two before the sprint that implements it.
This is not the same as waterfall inside a sprint. Discovery is continuous and its output is evidence, not a finished specification.
Lean UX
Lean UX, from Jeff Gothelf and Josh Seiden, overlaps heavily and pushes further: state assumptions explicitly, build the smallest thing that tests one, and prefer shared understanding in the team over documentation handed between roles.
In practice
Two things reliably break it. Designers pulled into the current sprint to unblock developers, which means nothing is ever validated before it is built. And research findings that arrive after the relevant decision has shipped, which converts research into an audit of things you can no longer change.