|time dilation or time dilatation|
|the principle predicted by relativity that time intervals between events in a system have larger values measured by an observer moving with respect to the system than those measured by an observer at rest with respect to it|
|time dilatation or time dilatation|
The relativistic effect of the slowing of a clock with respect to an observer. In Special Relativity, a clock moving with respect to an observer appears to run more slowly than to an observer moving with the clock. In General Relativity, time dilation is also caused by gravity; clocks on the earth's surface, for example, run more slowly than clocks at high altitudes, where gravitational forces are weaker.