A lacrosse ball is the solid rubber

Rubber

Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

 ball that is used, in conjunction with a lacrosse stick

Lacrosse stick

A lacrosse stick or crosse is a long-handled racket used to play the sport of lacrosse. Players use the lacrosse stick to handle the ball and to strike at opposing players...

, to play the sport of lacrosse

Lacrosse

Lacrosse is a team sport of Native American origin played using a small rubber ball and a long-handled stick called a crosse or lacrosse stick, mainly played in the United States and Canada. It is a contact sport which requires padding. The head of the lacrosse stick is strung with loose mesh...

. It is typically white, but is also produced in a wide range of colors.

The old NCAA specifications are:
Weight: 140g - 147g
Diameter: 62.7 mm - 64.7 mm
Rebounce: From 1,800 height 1,092 - 1292 mm (70% rebounce from falling point)
Rubber content: 65%

The new NCAA year 2000 specs states:
"Section 17.