In the ScrumProcess, the larger of two InspectAndAdapt cycles are called Sprints. Sprints are 30-days* (WhyThirtyDays) in length, and must result in a potentially shippable increment of software. (Of course, when using Scrum on non-software projects this rule would become "must result in something of actual value".)
During the sprint, the ScrumTeam is empowered to do whatever is needed to achieve the SprintGoal.
For the daily InspectAndAdapt cycle, see DailyScrum.
ScrumMethodology uses 30-day iterations called 'sprints'.
Another use of the word sprint has sprung up in the Python/Zope community, see PythonSprint.
Ham Radio Morse Code operators have 'sprints' where they make as many contacts as possible, at very high speeds. See the Fists CW Club http://www.fists.org for more details.