1) In physics, spin is the velocity of rotation of something around a particular axis. Spin is sometimes called angular momentum , which is defined as:
The underlying principle can be illustrated by the spin of a figure skater with outflung arms, considering the spinning object the skater's hands and the body the axis. Velocity is inversely proportional to the radius, increasing if the radius becomes smaller and decreasing if it becomes larger. Similarly, the distance of the skater's hands from his body controls the speed of the spin: as the skater brings the arms in closer to the body (at a smaller angle relative to the body), the speed of the spin increases and as he moves them farther out (at a greater angle relative to the body), the speed of the spin decreases.
Spin of subatomic particles is measured in multiples of a unit called the Dirac h, or h-bar.
2) In public relations and journalism, spin is the selective assembly of fact and nuance to support a particular view of a story.