Dictionary:Period (T)

1. The time T for one cycle. The time for a wavecrest to transverse a distance equal to one wavelength, or the time for two successive wavecrests to pass a fixed point. For a monochromatic wavetrain,

$T={\frac {1}{f}}={\frac {\lambda }{V}}={\frac {2\pi }{\omega }}$

where f=frequency, $\lambda$=wavelength, and V=phase velocity. See Figure W-2.

2. A major standard geochronologic time unit; see stratigraphic classification and Appendix I.