pendulum
/ˈpendjʊləm/noun
1- a weight hung from a fixed point so that it can swing freely backwards and forwards, especially a rod with a weight at the end that regulates the mechanism of a clock摆; 钟摆。
1.1
- figurative used to refer to the tendency of a situation or state of affairs to oscillate regularly between one extreme and another〈喻〉摇摆不定的事态（或局面）：
the pendulum of fashion.
变幻莫测的流行式样。
USAGE
The use of the pendulum for regulating clocks depends on the principle, discovered by Galileo c.1602, that for small amplitudes the time of oscillation of a pendulum depends only on its length. A freely suspended pendulum resists changes in its plane of oscillation, a fact employed by Jean Foucault in 1851 to demonstrate the earth's rotation.
派生词
pendular
adjective词源
mid 17th cent.: from Latin, neuter (used as a noun) of pendulus 'hanging down'.