top(redirected from off the top of (one's) head)
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top,toy with a tapering point on which it can be made to spin. Tops were known in antiquity and appeared in Europe during the Middle Ages; they are used today in many different regions of the world by both primitive and advanced societies. The principle of its motion is utilized in the gyroscopegyroscope
, symmetrical mass, usually a wheel, mounted so that it can spin about an axis in any direction. When spinning, the gyroscope has special properties. Many spinning objects exhibit some of these properties; the rotation of the earth about its axis gives it the
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A rigid body, one point of which is held fixed in an inertial reference frame, and which usually has an axis of symmetry passing through this point; its motion is usually studied when it is spinning rapidly about the axis of symmetry.
The new quantum number associated with the top quark. Also known as truth.
1. short for top gear
2. Cards the highest card of a suit in a player's hand
3. a platform around the head of a lower mast of a sailing vessel, the edges of which serve to extend the topmast shrouds
4. Chem the part of a volatile liquid mixture that distils first
5. the high-frequency content of an audio signal