Degradation

In chemistry and biology, degredation is the decomposition of a chemical compound by stages, with well-defined intermediate products.

In telecommunication, degradation, which may be categorized as either "graceful" or "catastrophic", has the following meanings:

1. The deterioration in quality, level, or standard of performance of a functional unit.
2. In communications, a condition in which one or more of the required performance parameters fall outside predetermined limits, resulting in a lower quality of service.

There are several forms and causes of degradation in electric signals, both in the time domain and in the physical domain: runt pulse, spike, jitter, wander, swim, drift, glitch, ringing, crosstalk, antenna effect , phase noise

Source: from Federal Standard 1037C