Definition
The time required for one complete cycle of a repeating event, such as one full oscillation of a vibrating object or one full cycle of an alternating current waveform. Period is the inverse of frequency: if frequency is the number of cycles per second, period is the number of seconds per cycle.
Plain English
How long one full cycle of something takes before it repeats. If a wave or vibration goes through one complete back-and-forth motion in half a second, its period is half a second.
Context Anchor
Seen in discussions of aircraft vibration, electrical signals, radio waves, and aircraft stability when something repeats in a regular pattern.
Derivation
From the Greek 'periodos,' meaning 'a going around' or 'circuit.' The aviation and engineering use keeps that sense — one complete trip around a repeating cycle before it starts again.
Why Pilots Care
Knowing the period of a repeating motion can help identify whether a vibration, signal, or aircraft movement is normal or needs attention.
Analogy
A swinging pendulum has a period: the time from one far-left swing, across to the right, and back to the far-left point again.
Intuition Check
Period does not mean punctuation here. In this context, it means the time for one complete repeat of something that happens over and over.
Example Sentence 1
If an alternating current completes 60 cycles every second, its period is one-sixtieth of a second.
Example Sentence 2
The aircraft's phugoid oscillation has a period of several seconds.