Cross-functional team
A team that collectively has all the skills necessary to create a product Increment without depending on people outside the team.
What it means
Cross-functionality is a structural requirement in Scrum: it lets the team plan and deliver value each Sprint without waiting on external handoffs, which would otherwise introduce delay and misaligned incentives.
It does not mean every member can do every task. It means the combined skill set of the Developers covers design, build, test, and often deployment for the increments the team is responsible for.
Common mistakes
Organizations sometimes violate cross-functionality by keeping specialists (like a shared DBA team or a separate QA department) outside the Scrum Team, recreating the handoff delays Scrum is meant to remove.
Example
A team includes a designer and a tester as full members instead of routing design and QA requests to separate departments.