a wheeled vehicle that has two wheels and is moved by foot pedals | a swiveling metal rod attached to a bicycle or motorcycle or other two-wheeled vehicle; the rod lies horizontally when not in use but can be kicked into a vertical position as a support to hold the vehicle upright when it is not being ridden |
a single complete execution of a periodically repeated phenomenon | |
a periodically repeated sequence of events | |
a series of poems or songs on the same theme | |
an interval during which a recurring sequence of events occurs | |
the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz) | |