the relative speed of progress or change | a wheeled vehicle that has two wheels and is moved by foot pedals |
amount of a charge or payment relative to some basis | a single complete execution of a periodically repeated phenomenon |
a quantity or amount or measure considered as a proportion of another quantity or amount or measure | a periodically repeated sequence of events |
a magnitude or frequency relative to a time unit | 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) |