陀螺或旋转陀螺是一种玩具，古称千千。它可以绕着中心轴旋转，平衡于陀螺尖端的一点。陀螺是在许多考古遗迹里最古老的、可被鉴定的玩具之一。自古以来，陀螺也时常被当做赌博与预言的工具之一。有些桌上角色扮演游戏仍旧用陀螺来制造乱数。使用同样的道理，也可以使图钉旋转。

陀螺的旋转功能是依靠着陀螺仪原理，将细线紧绕在陀螺的圆柱部位，用力拉甩在地上。大多时候，陀螺会先不稳定的摇晃在地面上，直到陀螺尖将陀螺撑起立直。经过直立的旋转了一段时间，陀螺的角动量会渐渐地减小，导致越加明显的进动现象，终于在最后激烈的翻跳后，倒落于地上。

A top is a toy designed to be spun rapidly on the ground, the motion of which causes it to remain precisely balanced on its tip because of inertia. Such toys have existed since antiquity. Traditionally tops were constructed of wood, sometimes with an iron tip, and would be set in motion by aid of a string or rope coiled around its axis which, when pulled quickly, caused a rapid unwinding that would set the top in motion. Today they are often built of plastic, and modern materials and manufacturing processes allow tops to be constructed with such precise balance that they can be set in motion by a simple twist of the fingers and twirl of the wrist without need for string or rope.