Jitter is variability in latency, or delay. Jitter is also the tendency towards lack of synchronization caused by mechanical or electrical changes. It is the phase shift of digital pulses over a transmission medium (Newton's Telecom Dictionary, 18th Ed.). In lemans terms, jitter is the short term "shaky" pulses or slight movement in time or phase that can introduce errors and loss of synchronization on an amplitude modulated signal.
If there is jitter on a transmitted signal it could lead to the degradation in system error performance, slips in the timing of a circuit which would lead to errors on the circuit and the distortion of the analog signal after the decoding or the digital signal has taken place. …